I'm thinking since I have two identical 2.4 MacBooks (last ones made mid-2010) I will put one on SL and one on ML and do some real world tests for the forum to solve this issue once and for all. Especially since I feel as if my laptops are running sluggishly under ML and I have wanted to try SL again ever since I upgraded all my machines. This will be good for everyone.
For me, I like the new features in ML because it really helps me connect all my iDevices with my iMac, and MB's. It makes social integration easier across the platforms and it's a great set of new features. With that greatness comes a price however. Bugs yes, but more-so than that BLOAT. ML is like a big custom GMC Suburban with a bunch of features and SL is like a little lightweight Lotus with a turbocharger.
I expect I will be happy again with the speed of my machines when I downgrade, which I have not been since I upgraded. I have a 27" mid-2010 iMac with 8gb, a 21.5" 2011 iMac with 4gb, two mid 2010 2.4 MB's with 8gb. NONE of them have ran as well as they did on SL, all feel sluggish even after disk repair and other proactive efforts.
There is a very well defined and documented wifi issue in ML that has driven me insane. Every program I use has been upgraded to work with ML so no issues with compatibility. Just a few bugs and sluggish bloated performance keep me from liking ML the way I'd like to and I think SL is going to be less bloated and snappier for me so we will see. I'll do the downgrade in a day or two on one of my MB's and do a fresh wipe on the other and re-install ML since I can restore from time machine backup if I decide to keep running ML.