However, virtually all pro programs greatly benefit from lots of (fast) RAM, which still is prohibitively expensive for the iMac when you go above 16GB .
Remember, it is still a pimped out laptop on a stand .
16GB isn't small potatoes in terms of memory capacity though, and it can do a lot. I'm not saying there aren't applications that can gobble up RAM, or utilize more if it's there, but that's something that has to be taken into account for the specific use.
Now as to the physical memory configurations in the new iMacs, that's a function of the number of memory slots and the largest sticks that can be placed in them (Samsung actually has higher density RAM chips, which allows them to create sticks @ 8GB each, but they're expensive and hard to find last I checked).
As per it' being a pimped out laptop, I would have agreed with that a few years ago, but not any longer, as they're using consumer grade desktop parts now (i.e. LGA1155 sockets now, and they're not the mobile versions).
Also, photo editing requires a display better than the iMac's, 3D editing and rendering suffers from (comparably) insufficient GPUs, too few cores and CPUs generally slower than a mid to high end MacPro's; video editing requirements are similar, I assume .
This is the one valid complaint to professional photo editing (would also apply to less demanding video editing as well). I don't see the iMac as a contender for rendering at all (GPU is fixed, and not enough cores).
But when I think of it as a photo editing station, it can actually do it. Granted, the monitor is glossy (where I see the validity of the complaints for both this and light duty video editing), but you can add in a professional grade monitor (you'd have to do this with a MP anyway). Now consider that the iMac is cheaper, and it can actually begin to look attractive for some users that previously would have had to buy a MP (3.1Ghz 27" is only $1999USD = most expensive model, which is a faster clock than the base MP right now).
The built-in monitor can still be used for other things (use a dual display configuration), which would cost even more funds on the MP.
Another thing to note, is that there is already a company that makes a Anti-Glare screen sheet that can be applied to get a matte coating on a glossy iMac screen. Personally, I think Apple should either go back to matte, or at least provide it as an option (even if it's on the pricey side at say $200, it's still worth it for photo and video work at least).
Now I like PCIe slots my self, and happen not to be a big fan of an AIO system (repairs come to mind, as well as greater difficulty to upgrade). But I do see it's merits for those that won't get inside of them often, if at all (repair and internal upgrade limitations = acceptable compromise). Now given the current economy as well (seen lots of claims it's picking up, but the average citizen isn't seeing it here - not where I live or have friends/family anyway), cost is a greater concern that it has been in the past, and this is particularly the case with independents and SMB's in my experience.
I see the newer line of iMacs as the beginnings of a game change in the entry level workstation market (i.e. TB equipped AIO's or even laptops, so long as the software used cannot leverage true
n core multi-threading, and can accept a fixed GPU).
BTW, for the moment, I'll assume TB based graphics cards (meaning PCIe lanes are used to transfer data to an external GPU aren't going to fly well, particularly for fast motion graphics, due to the bandwidth limit of 800MB/s downstream). This should be more of a possibility as TB's bandwidth is increased though.
TB external HDDs are yet to come, and my guess is the price will at least be that of FW enclosures.
There's only a couple that have been announced, but the Promise Pegasus R4 & R6 are enterprise grade storage (fast, and uses a hardware RAID controller located in the enclosure). More peripherals, including storage should follow once TB equipped systems show up in users' hands (chicken and egg argument still applies, but Intel has managed agreements with peripheral makers as I understand it). So it's just a matter of time.
As per cost, you may be right (economy of scale is meant to keep it cheap, but there's nothing actually for sale yet). But for what they can get from it, a $50USD or so premium may not seem that bad (can daisy chain, granted so can FW, but it's faster and can even be used to attach an external monitor, which FW cannot do).
Fast external storage - or rather space for project files and scratch - that goes beyond what a tower offers , is mainly a concern for pro users who work on location.
Apart from that, fast storage doesn't do much for you, or else you are way out of iMac country anyway .
TB based storage and a laptop would be a great combination for location shooting, that's for sure (far easier to lug it around an airport).
But it's also a means of both larger capacity and speed than what's possible via internal drives in a TB equipped AIO as well. Even photo and audio editors need more than a single disk speeds to work well as I understand it, and video editing (even light duty), certainly would be able to utilize it.
To me, it's a matter of getting past current concepts of what a constitutes a workstation. Xeons aren't actually the defining characteristic for creative professionals, as they don't require ECC, nor are PCIe slots so long as there's an alternative method of bandwidth. TB provides this, so it's changed matters quite a bit for the low-end MP user (aka entry level workstation user).
If you've noticed, Intel's even brought out LGA1155 based Xeons to fill this market (those that do need ECC). Now given the increasing core counts, this is going to change even further (i.e. those that currently need a DP system may not for much longer, say once each core hits 8/12 cores per die, which isn't too far away).
TB on the iMac might be an attempt to streamline the consumer experience in the future, when and if the peripherals like monitors and iGadgets have caught up, yet the real work is still done with more flexible and powerful machines.
They've introduced it to the laptop, AIO, and device market to increase the adoption rate (professional laptop users such as video editors doing location shooting can actually utilize the bandwidth). Consumer users will be attracted to the convenience, and that will help improve market penetration, which will translate into fast profits, and cement it's place (continued profit generator for future quarters).
Now for users' that need more than an entry level workstation, a unit with PCIe slots makes more sense (can get better I/O as well as more memory and core counts). But this is a separate group of workstation users.
This is where I actually see the difficulty (TB + AIO = redefining the entry level workstation user vs. mid-level and high performance workstation users).
