I'm running an 'idle test' as I'm not yet actively using my Jolla as primary phone, so conditions are: wifi and 3G enabled (phone all time in home WLAN coverage), gmail+twitter sync activated, developer mode. Only activity was periodically peeking device screen and logging via WLAN to ssh.
With these settings, in about 1 day and 17h after I killed the TOH daemon the battery went *only* from 96% to 74%.
I'd like to test a few things on the phone but I'll probably hold my horses and wait to see first when the low battery warning will show up.

Update: uptime since stopping tohd is now 3 days and 13 h, and battery is at 57%. Idle test continues...