I'm pleased (and a little shocked) to report just how well this is working for me. I've spent the last couple of days making sure I back out of all apps so my little Active App Manager icon reads 0 before I turn off the screen. The battery savings has been quite impressive.
On a normal work day I take the phone off the charger at 9 (after rebooting, of course!) and run it all day. I text, make the occasional call, check Facebook, email throughout the day and evening, watch at least a couple short You Tube videos, take some photos (which usually require editing and emailing), make chess moves, surf the net a couple times and stream music (to my Bose SoundLink, Rhapsody, offline mode) for several hours.
Today is a 'normal' usage day where I have done all the above. It's now 9 p.m. and I'm usually down around 30 - 35% at this point. I'm at 62%! To quote one of my favorite movies, "By Grabthar's Hammer... What a savings." (Bonus points if you know that quote!)
Needless to say, I'm thrilled. I'll watch this some more but I'm quite surprised to find out just how much battery was being used by apps that were residing in the RAM even though they were (supposedly) not using any CPU while dormant.
If someone else tries this I would like to hear if you are seeing any improvement.
Another update: Three hours later, texting, surfing, streaming music for 3 solid hours, down to 51%. I can't remember the last time I went home from work with 50% battery left.