I think for what you need iPhoto is the best photo organizing tool.
I just finished the free app iSlimPhoto -- please go ahead and use it to slim down your iPhoto library. It will take away 40-80% of its weight, without any noticeable loss in quality on your monitor (multi-megapixel images are resized anyway to be displayed on your monitor).
Just reading your page quickly, I don't think that it does what the OP was asking for: his concern was that his "BIG" library was too big and your App doesn't do anything about that per se, but merely makes a down-rezzed duplicate copy of the 'BIG' library: it doesn't appear to actually change Mr. BIG.
And since this means that you're not destroying the originals, that's not a bad thing IMO (its a good thing!) - its simply that this wasn't what the OP was looking for.
I hate this attitude. Yeah, harddrives are cheap, so lets design programs so they just waste harddrive space for no good reason. $100 for an external drive is still $100 that could have been spent elsewhere if the software wasn't dumb. But I guess that's the 'mac way' .. it just works! ?? Picasa doesn't add doubles of all your photos, it leaves em where they are. It doesn't even save your edits as additional photos, it just keeps track of what filters you've applied and displays them as such (unless you specifically export the files/tell it to update) so it's nondestructive without eating up your hard-drive.
Everything in life is a trade-off; better get used to that.
The trade-off here is that iPhoto does eat space, but it leaves you with an unmodified original and a modified version - - both of which are not in a proprietary data format. As such, you're
not STUCK with iPhoto for the rest of your (and its) life.
That's the '
good reason' right there.
I think I'm going to hop on Picasa for the Mac when it comes out..
You're free to use whatever you like.
But please remember to refrain from whining if a problem you've now been warned about comes back to bite you in the ... posterior regions.
To that end, before committing a lot of labor to Picasa (or anything else) you may want to check to see what it has today for its "exit migration" strategies, such as a tool that faithfully preserves both your originals as well as applying all of your modifications and creating for export a full file version of your modified....and capable of being automated for your entire portfolio.
If that sort of tool doesn't exist, then you may be very well looking at having to abandon all of your file modifications at some point in the future...
And that's your trade-off for using this tool to save some HD space today.
FWIW, I've observed is that while the iPhoto data directory is a big chunk of where I'm using storage capacity, its not necessarily because of 'inefficiency' but because of heavy utilization: my iPhoto library currently has 22,000 images in it and yet the Originals folder consumes roughly 70GB, which means that if I modified 100% of my originals, then the total disk consumption would be ~150GB in total. In the big scheme of things where a 1TB drive now costs $110, that's on the order of ~$20 worth of storage.
I'm not about to complain about today's storage space costs, because I still have a few CD-R disks that when new cost me
$10 per disk.
-hh