Took me a lot of learning to figure this all out bud so hope you like it.
1) Buy ~1700mah uprated battery from Mugen, no cheap chinese knockoffs.
2) Use rommanager to find a better rom, like IceCreamSandwich.
3) Whenever you install something run the Task Manager from Astro. I've noticed some task managers don't show services or processes and tend to confuse matters.
Check to see if it's added a service
. If it has remove it. You have to remove because the app will only start it again. It's bummer not being able to use skype & fring but that's their fault. You might also have to avoid widgets and K9mail.
Also check if you can to see if the backgrounded apps are coming out of suspend and using CPU %.
Backgrounded apps and services are different things. Also, potentially (I think) you could have processes that might not advertise as either but personally I'm not worrying about that just yet.
My DroidPro arrived today and I think with all this it should be behaving similar to my GalaxyS1 (i9000). The i9000 is similar to a S2 on a fresh install but after you install a few things you get lag that you don't get on a s2 due to that 2nd CPU.
Hope this helps,
open for tips