I have an AT&T Pre 3 on AT&T in Oklahoma. Network is pretty spotty but overall passable. It is the stock webos with no modifications or altered settings of any kind. I tested my battery overnight, having charged it on my touchstone to 100% before midnight and took it off to sit until I woke up. By morning, it was at something like 20%.
Since reading this thread, I have put all my email sync on 1 hour and disabled wifi when screen is off. Woke up in the middle of the night about 3am and took the phone off the touchstone. Three hours later, it was still at 100%. Made a phone call, checked email, sent a text. checked traffic (on People finder not maps) and checked battery repeatedly until just after 8am and the battery was at 92%. For me, that is very good. I am now very optimistic.
Next, I will install preware and govnah and see how well that helps (probably will add uberkernel as well).
update: for the last 2 hours, i have downloaded an app (with very bad data connection), reviewed several emails, downloaded a couple of large images off facebook, shared said pictures with several friends (lots of screen active time), played 10-15 minutes of games, a couple of phone calls and received a couple of texts, and it used 23% more power. For all it did, that still does not seem unreasonable. maybe it will stay in my pocket a bit more for the afternoon and we will see where it is.
another update: took the phone off the charger at around 3am and did nothing with it until 9am. It was down to 70%, so that is about 5% per hour, but that is not consistant. Even with the initial drain in the morning, it still seems to last the day, unless I want to use it for a lot of calls and data, then I must charge it while at work. However, I do not see that it is much worse than my samsung s3 on at&t. my coworkers say they have to use a special app to turn off various radios while in their pockets and it still uses more than 1% per hour, even with this tool, and their battery is like twice the capacity of the pre3. So, not certain it is all together out of line with competition. That said, 7% consistently used when not using it - you better have some touchstones lying around and enjoy that aspect of the pre design.