For me file sizes wouldn't really be an issue. I'm currently using uncompressed RAW, so could just switch to cRAW so the size wouldn't be that much different.
For filesizes, maybe Sony will release a firmware that will allow reduced resolution RAW files, like you get on the new Canon 5Dmark2
As for processing, my PC is already up for it - and CS4 looks like it might hold the key to processing those large images (see my post on GPGPU within CS4 @ http://www.dynaxdigital.com/index.php/topic,6878.0.html
I have 128 streaming processors on my graphics card just waiting to be used on those large A900 files, and it would make me feel much better to put them to good use
It appears that CS3 and CS4 is already 64bit on Windows platforms which is great news, RAM is just so cheap nowadays. There still appears to be no word from Adobe on 64bit support for Mac, which seems odd as I thought Mac was the primary platform.
I think it's like all upgrades, the A900 will show some weaknesses in some of your lenses just like the A700 did, but just like the A700 you don't have to fix all of those at once.
I don't need 24MP, but probably didn't need 12MP either most of the time. There are two drivers for me to go FF, one is that BIG viewfinder (just looking though my Dynax 7 film camera makes me want to go FF), as well as the DOF.
It's a shame there's no pop-flash and the price is high and I can't afford it, but hey maybe my wife will get me one for my 40th next year
I can only ask