After all the talk about wakelocks, I finally downloaded better battery stats to experiment with.
After fresh boot I checked BBS Raw kernel wakelocks and found none.
Then enabled BT, checked again, again nothing. Enabled wifi, still none.
Then I killed the screen and went for a smoke. When I unlocked screen, I checked System Tuner Pro for sleep times and found none (as expected, with BT and wifi on). Checked BBS and found 2 of each mmc 0,1,2 with times of about 2 1/2 minutes each.
Then I turned off BT and again killed screen, and went for a smoke.
When I checked again, still no sleep time, and 1 of each of the pairs of mmc 0,1,2 had gone up to about 7 1/2 minutes while the other set still said 2 1/2, as before.
I assume this indicates that they were released when BT was disabled.
Next, I turned off wifi, killed screen, got coffee, puffed on E-cig
and then unlocked screen.
This time System Tuner Pro reported about 3 minutes of sleep time and BBS still showed all 6 mmc wakelocks with the same times as before (half of them @ 2 1/2 and the other half @ 7 1/2).
I don't really understand exactly how BBS reports, but it seems that all of the mmc wakelocks were released, and deep sleep mode was allowed.
I don't know if ths will help anyone, but all seems to be working fine here.