You've gotten so many replies, that I almost decided not to, but here goes.....
1. I started 2 1/2 years ago with the PN-20. Now you need to go there if you want to talk about battery life. It was terrible. However with the PN-40, we use both the rechargeable Li-on batteries or rechargeable Nimh. I would say 6 hours is good. Now we do keep it plugged in while driving in the jeep, unplugging when on a cache trek or hiking. Better life would be more desirable, but is tolerable now.
2. I haven't ever experienced this. We travel in our motor home 100% of the time so we've been all over the country and although I would think this could be attributed to the area you are in, we haven't found this to be an issue.
3. Nearly always get WAAS lock.
4. We keep a 16GB SD card filled with detail maps. Always have a PQ or 2 or multiple caches and routes loaded. Haven't seen this issue.
5. No knowledge on this one.
6. Just a little experience on this one. Have loaded a couple of maps acquired elsewhere and one jpg "map" with XMap for places out of country where I couldn't get anything from Delorme. Like all things, it works better the 2nd or 3rd time you do it as you get better. My experience limited, but it worked quite well for us.
Don't know what else to say, we love our PN-40 and use it nearly every day.