Well, let me get the ball rolling.
The new iMacs are beasts. Very capable and
you would have no problem with track counts. You should even be ok working with orchestral
samples and high track counts due to the multiple cores Logic can address. Expendability,
while still more limited on the iMac, is less so with the introduction of Thunderbolt.
Peripherals are now starting to appear. However, for audio, unless you're looking to buy
the Apollo with Thunderbolt option, FW and USB still rule.
I'm currently on a
2009 Mac Pro 2.26 with 12 GB or RAM and it's handling large orchestral templates very
well. My track count is VI's is easily into the 30s with a total VI/plugin count of
anywhere from 15 to 40 and doing just fine. Only upgrade I'm planning in the near future
is doubling the RAM to 24GB and contemplating and SSD for Start-up HD and Sample HD. Oh
yeah, it helps to keep your start-up drive (with Logic on it) separate from your Audio
Projects HD and your Samples HD.
With the MacPro I have the luxury of having
these components all internally and still lots of room for more expansion. Plus, no
built-in monitor gives me the chance to set up a matched dual screen, highly impractical
for the iMac. Though I recognize this is of little importance to most people.
Just a piano and some sketch paper please...