Under the theories of 'what can go wrong will go wrong' and a reluctance I have to messing with a well-running printing process (its always a PITA) is to create a temporary dual-boot system. I'm using the approach now due to an upcoming shoot I'll need to produce some prints from (upgrading from CS3 and Tiger).
You keep your existing system as is, but install Snow Leopard to a clean and formatted fast external drive (or internal one if a Mac Pro). Copy over any existing apps you need and then download the free trial version of CS5 to the new drive.
This way on a re-start you can boot to SL or your older system at will - and access any files back and forth. This allows you to try CS5 for processing & printing, etc w/o risking throwing an 11th hr monkey wrench into your existing printing process.
You can also process images in CS5, save them as TIFFs and the re-boot in the older system and print from your existing printing pipeline and older copy of PS.
The approach also allows you test-drive any apps you have or are thinking of getting (via trial versions) for issues with SL, etc - with zero risk. When all said and done and happy - you can make the move permanent, upgrade to a paid copy of CS5 and away you go (I'm actually keeping a bootable copy of my older system with apps - just in case).
I liked the setup so much (still very fast even over FW), that to make it simpler, I did a couple of updated clones of my existing Tiger (I know.. ouch) system drive (just in case) then re-partioned the drive with a a 10.6.6 startup 'disk', an older 10.4._ startup 'disk', and a third for shared files I might be working on at the moment. This allows me a simpler backup process as only have one physical (w/ 3 partitions) system/apps drive (vs image drives) to clone during regular backups.
Oddly enough, the setup felt a smidgen faster over FW vs. my internal system, despite its faster access speeds as the internal drive is a lower-capacity, slow 5400rpm unit with a small cache vs. the 1Tb 7200 rpm, 32mb cache unit I had running it via firewire. That said, it will easily do until I move to a Mac Pro later this winter. Still feels like a MUCH, MUCH improved machine. I am actually gobsmacked by how much better (speed, memory allocation, etc) 10.6.6. is, even running a hog like CS5, over the last version of Tiger running CS3. That and fact, so far, NO issues.
That said, I have not tried printing with CS5 yet so haven't set-up Epson drivers under SL as simply too busy prepping for shoot to go down what could be a long series of troubleshooting days. I'll save that for when I'm in the right mood.
