Apple Logic Pro /LogicExpress Discussion

Hi,

I'm currently running Logic Pro (8, but will be upgrading to 9 with the 
new system) on a 2006 MacBook Pro with 2GB of RAM and a 350GB hybrid 
disk.  I run into the dreaded system overload with some regularity.  I 
don't run very high track counts and do very little recording, but I 
tend to use a lot of softsynths (mostly from the NI Komplete suite) and 
use a very large array of effect plugins per track.

I've been saving up to replace this machine, and was targeting the 
newly-released 2011 iMac 27" with the 3.4GHz quad-core i7 Sandy Bridge 
processor, 4GB of RAM (that I was going to upgrade to 12GB after the 
fact -- the system maxes out at 16GB), the 256GB SSD + 1TB HD disk 
configuration and the 2GB GDDR5 Radeon HD 6970M.  With the AppleCare, 
this clocks in at $3098 + tax.

However, it's recently come to my attention that a local shop is selling 
a gently used 2008 Mac Pro.  It has two 2.8GHz quad-core Nehalem Xeon 
processors (8 cores total), 4GB of RAM (maxes at 32GB), a 320GB hard 
disk, and an NVidia 8800GT with 512GB RAM.  They'll warranty it for 90 
days and you can pay extra to extend the warranty if you like, although 
it'll be their warranty rather than AppleCare.  They want $1699 + tax.

Among my geekier-than-me friends, there's been a big debate about the 
CPUs in these two machines.  The iMac's Sandy Bridge architecture 
supports SVX instead of SSE, which apparently will, once apps are 
updated to support it, allow it to process eight instructions per cycle 
rather than four, according to them.  Given that it's already clocked 
faster than the Xeons in the Mac Pro, that would make it noticeably 
faster CPU-wise.  The rest of the Mac Pro's architecture is slower as 
well -- the memory bus isn't as fast, the 8800GT is about half the 
performance of the 6970M, etc.  However, the Mac Pro offers more 
expandability -- I could add a RAID card, I could have several internal 
disks, I can upgrade the video card, etc. And if Logic Pro doesn't 
support SVX, then I expect that having twice as many cores at a slightly 
slower speed might be a CPU win.

But the difference in price is also a big factor -- with that much less 
money I could perform a lot of ugprades (note that I'd have to eat away 
some of that buying a monitor, but you can get a 27" LCD of good enough 
quality for me for $300, and getting a disk system comparable to the one 
I was speccing for the iMac would take away more of that, but I could do 
this flexibly over time).  I mean, at $1699, I wouldn't be particularly 
upset if I had to upgrade it after only say three years, whereas at 
$3100, I'd want the iMac to last me a good five years, much as my 
MacBook Pro did.

My only real bottleneck is Logic Pro, though.  This is going to be my 
studio machine.  I mostly game on the Playstation 3, and I have an iPad 
that is fine for my needs for travel and surfing.  So I'm wondering if 
any of you have any thoughts or real-world experience between these two 
machines as they specifically pertain to Logic Pro, and if anyone knows 
what the status of this SVX issue is with Logic Pro -- if it's something 
that I should expect to see coming down or that's even already there, or 
if it's even relevant to Logic Pro's architecture, or if having twice as 
many cores will still be better when running a ton of plugins.