Successful downgrade from Lion to Snow Leopard?

Question

I will get to my question at the end, but first I must explain the situation:
I have an MBP Intel Core 2 Duo, circa 2006.
The case was falling apart so I bought a new MBP Intel Core i7, September 2011 model.
The new MBP came with Lion, which to my horror did not support PPC applications.  I know some of the Mac OS hobbyists will say 'get over it'.  However, I use Macs professionally and since I want to eat (so to speak), I must work, and to work efficiently I need Rosetta because there is quite simply no replacements available for some of my quirky software.
Lion has a couple of ways of stopping you upgrading back to Snow Leopard.  Here is a simple way to do it, which allows you to keep Lion.
Boot lion and use the disk utility to create a new partition:  I took 400 GB for the new SL partition and left Lion with 100 GB.  Lion is pretty neat in allowing you to repartition on the fly.
Do the latest software update on the old computer (10.6.8).  Restart new computer in target disk mode and connect to old computer using a firewire.  On the old computer boot up Carbon Copy Cloner (freeware).  Set the old computer as source and the SL partition as traget on the new computer.  Simply accept all the default settings on CCC and let it to Clone (ie. backup) the source onto the target.  CCC will generate an exact copy of the contents of the old computer's hard drive on the SL partition on the new machine.  I believe it will aslo transfer FileVault protected accounts even if the user is not logged in.
Shut down new computer.  Reboot holding down the optino key.  For some reason the new SL partition was named IEF Drive (or something similar, I cant remember because it reverted back to its original name after a restart).  The machine will boot into SL.  Go to system preferences and select SL partion as your startup disk.  All done in about 4 hours, most of which is waiting for CCC to finish!  Whoopeeee.
So far it seems to me like EVERYTHING works just fine.  I was particularly suprized that the Thunderbolt port was able to drive my external display either via vga or hdmi adaptors.  I half expected that not to work because it is a brand new feature.  Of course, it may not work with a Thunderbolt display. Howerer, since the machine is duel boot and I can go to Lion any time I feel like it.
I did have to reinstally Application Enhancer so that my Unsanity Haxies would work, but you have to do that after any migration.
Performance
Geekbench 32 bit overall score:   lion, 8473:  SL, 8321
Novabench:  lion, 882:  SL  859
At first I had the impression that Lion was a bit swifter on start up and GUI response, so I used migration assistant to migrate my old computer user account onto the Lion partition.  As expected all the login items and extra system services that came across from the old machine had a penalty for start up and shut down.  After timing both I find that SL is slightly faster up and down than Lion.  Even so, I am sorry not to be able to use Lion as I liked the look and feel of it right from the get go.
Never mind ...its function over form for me every time
Now my question is to ask whether others have exposed any weaknesses in a SL down/upgrade?  It would help if you would post here so that I can head off any problems before I discover them in a critical situation. 
Also, do the experts think SL will match the 64 bit performance of Lion, which I was unable to test because I am too mean to pay the 19 bucks for Geekbench?
Finally, I must say that after many years of daily use on countelss machines CCC has never once let me down, unlike TimeMachine.

Answer 1

I had said that the "function" of the user preferences in the ByHost folder won't be preserved on a different computer, not that the files wouldn't be there!
The ByHost folder contents are accurately preserved in a CCC clone, but the .plist files themselves are tagged with the "hardware UUID" of the particular computer they were made on, and will only function on that computer. Peek inside at the names of these preference files and you'll see.  It's not an important issue in practice.
From Mike Bombich's CCC Knowledge Base, here:
Can I back up one computer and use the clone to restore another computer?
As long as the architectures match (e.g. intel vs. ppc), then the answer is **probably yes**. However, there are two caveats.
    Some of your preferences on Mac OS X are considered "host-specific." Preferences such as these will be ignored if you boot your cloned operating system and data from another machine. For example, the screen saver preferences are host-specific -- if you boot another machine from your bootable clone and the screen saver kicks in, you will notice that it has reverted to default settings. Do not fear that you have lost any data, your original preferences will be "restored" when you boot again from your original computer. To learn exactly what preferences are host-specific, navigate in the Finder to your home directory, then to Library/Preferences/ByHost.
    Don't install older versions of Mac OS than what comes with your computer. When you get a brand new Mac from Apple, it usually has a specific version of Mac OS X installed on it, and further, a specific "build" number. If you install an older version or build of the OS, for example by cloning your older Mac to it, then it may behave unexpectedly. When migrating your old Mac to your new Mac, be sure that your old Mac has been updated to at least one later release than what came on the new Mac. For example, if your new Mac came with 10.4.7, update your old Mac to 10.4.8 before migrating. If such an update is not available, use the Migration Assistant instead.