From my post in another thread:
I don't use an external monitor, ever. I do regularly connect to projectors and Apple TV's in conference rooms with the rMB though, either wirelessly or via the Apple multimedia adapter (HDMI version).
The reason this is relevant to this thread is because, like
@sracer, I attempted to use the 12.9" iPP as a sole device, setup remote desktop access to my iMac, and did the thin client thing. It worked ok. I have a 1Gbps up and down connection at the home office where the iMac is located, so connection speeds were never ever a problem, but the experience was. it wasn't optimal in any case. When using the iPP this way, it just becomes a laptop, and not a very good one. It loses the iPad part of itself. Doing this convinced me that the approach Apple has taken thus far seems to be the best one. As an iPad, the 12.9" is huge and ungainly, it is no longer this amazingly powerful thing you can't believe to can hold in one hand (because you can't anymore).
So I then said to myself, "ok, you've got this big huge iPad, why not get a laptop to match it to emulate your previously almost perfect setup, but super sized?" So I bought the new 2016 15" MBP. AWESOME computer, I must say! BUT - after a week using the setup, lugging around the 15" MBP and 12.9" iPP and using them exactly the same way as I did the rMB + iPad mini 4 combo, it became ridiculous.
I couldn't even use the MBP on the train or plane, no point in even trying as I don't travel first class, and the iPP was more cramped to use than the rMB! I wasn't getting anything more done, actually less productive because I do actually do a lot of work on trains and planes, and having a laptop that could almost serve as my iMac replacement but wasn't any better at being my professional laptop than the rMB was not only unjustifiable, but even more so I wasn't getting that joy of ownership or use that I got every time I pulled out my iPad mini 4 or rMB. These two devices are much more magical, and thus much more of a joy to use. They pack an incredible amount of computing and productivity power in tiny little form factors that amaze every time you take them out.
So I returned the 15" MBP and 12.9" iPP and returned to the 12" rMB and 7.9" iPm4. Never been happier! The whole experience (I won't call it an ordeal, because even though it felt like one a lot of the time, I can see really good aspects of the large iPP) allowed me to appreciate the smaller devices like never before.
Just another nitpick maybe, but another really irritating thing with the 12.9" was the lack of differentiation in app usage experience. Yes, split screen was much better on it, but as
@sracer pointed out, the experience for using it leaves a lot to be desired. Apps themselves are exactly the same, just...bigger. No optimized UI for the double amount of space to be utilized, just the exact same thing scaled. Actually felt easier to use apps on the smaller iPads, especially the mini.
For leisure and entertainment, it was the same. Games just looked blown up and not as crisp, and the controls for them were harder to use, because they were farther apart. Comics and books, the same.
It seems like they optimized the 12.9" to do only one thing better than its smaller siblings, split screen, and nothing else. IMHO, it isn't enough to sacrifice everything else. This new 10.5" rumor though, is interesting, if they fit the same resolution as the 12.9" in a 9.7" chassis size, it could get interesting. Personally though, I am hoping for a proper 7.9" iPad mini Pro release alongside, even though it is probably pie in the sky...