Run into a strange problem that I believe coincides with either turning on or off this option.
Since then (and for the past few days I had turned it off, have done more than one full power-off and startup since then, no automatic running of task killers), I've sometimes gone 2+ days without needing to recharge my battery, but not for a good reason - it seems that my device has started going into a deep sleep when left alone for an extended period (over 10 mins, possibly under 1 hour) and despite having set it up not to kill wifi I've had it doing so repeatedly.
It's not just a network thing though, as the Alarms app has stopped waking up when set in this condition too (I overslept the alarm by a bit, short-pressed the power button to turn the screen on, then suddenly out of sequence the alarm just goes off - not in response to a snooze interval).
Normally that only happens if power completely dies whilst it's resting and I turn the phone back on again, but this isn't a full loss of power (like a loose battery might cause), as it doesn't need a full boot up or entry of pin.
I've just re-enabled the code again today and will be watching to see if it behaves itself any better, but just a warning in case you see similar behaviours. Other than using this code, my device is still running 1.6 with no firmware updates.