Alright, I may have found what's going on with Deep Sleep mode, it may just have to do with ICS itself rather than just the ROM. On thekraven's Cold As Ice and Quattrimus CM9 (both the latest alphas), both stay locked at minimum CPU regardless of the time the phone spends idle...UNTIL I put it into airplane mode. Then it sleeps as it should.
On CAI I found that BetterBatteryStats reported an MMS Connectivity (or similar, I remember those words) process causing a Partial Wakelock which had apparently lasted for 2 hours, i.e. the whole time it wasn't sleeping. This prompted me to try airplane mode, and voila! Gave it a minute or two and it Deep Slept.
What's strange is, after a reboot there were no extended wakelocks being reported by BBS, yet the phone refused to Deep Sleep unless I put it into airplane mode. Quattrimus has provided identical results, sans the extended wakelocks, which it too is apparently free of.
Anyone have any ideas what could be connected to the cellular connection that's keeping the phone awake? My specs:
CPU: 480/729 SmartassV2
ROM: Quattrimus CM9 10a
Phone: lol LG Optimus V