Just what do you think their "extensive testing" is worth anyway? They tested CS3 "extensively" for Leopard and gave it two thumbs up, then a few days after the official release of 10.5 it turned out that if you were using Leopard + CS3 and saved Photoshop documents to a network share, the files became corrupted beyond repair. That's an extremely serious issue (it destroyed your effing files!) and dead easy to spot for anyone who used it for half an hour, yet it slipped through the "extensive testing". They addressed that with a maintenance update after a few weeks. CS3 *still* doesn't work properly on Leopard, it's a known problem that a few of the apps (Dreamweaver, Flash, possibly more) hang for a minute or two on launch unless you disable the Welcome screens, and compatibility with Spaces is dodgy at best. It's not like SL can make CS3 crappier on Mac than it already is (the Windows version always served me well, though).
Adobe are a bunch of clowns... out the companies whose software I have to use against my will in my line of work (Microsoft, Steinberg etc), Adobe are the absolute worst yes, worse than M$. After the Macromedia acquisition they've become a complacent dinosaur that makes Microsoft look like a young sly go-getter... Adobe makes awful, insanely overpriced bloatware with barely any new features from version to version, the only thing you get is the same ancient bugs that they've left unfixed for aeons. And if you use CS on both Windows and OS X you have to buy two CS licenses (all the music/audio software I use ships with the PC and Mac versions on the same media and allow for two installations with any PC/PC, PC/Mac, Mac/Mac combo). Adobe is in dire need of serious competition that brings them down to planet Earth... or better yet, six feet under.
Oh, and their pesky little Flash plugin is the #1 source of crashes on both PC and Mac... nice job.