You're probably right, and battery life varies a bit day-to-day. I haven't done a formal test to double check my statements above, more just a feeling.
I've had the phone for a while and the battery has gone through many cycles. It has definitely lost some capacity.
The modem asserts a wake pin when you receive an SMS or phone call, causing the SoC to wake up. Services that rely on data (IM, e-mail etc.) don't wake the phone up (they will rely on periodic wakeups in the future, but there's no infrastructure for it yet).
An update that makes communication with the modem after resuming from system suspend reliable has been deployed today (previously it would often fully reenumerate and cause various troubles in the process, now it's instant).
https://forums.puri.sm/t/modem-draining-the-battery-very-fas...
https://forums.puri.sm/t/current-l5-idle-battery-life/14772