My wife has a Hero with battery issues. Here is my thought - could this be location or signal strength based? A few years ago I practically caught my pants on fire with a Moto Razor in the basement of a hospital. The phone had no service and went through a full charge in less than 45 minutes.
The wife's had multiple days at work where the thing turns itself off from a full charge after ~5 hours and minimal use. I used the phone for the first week "setting it up"
and didn't really have an issue, but still swapped in SMS Chomp before turning it over to her. This weekend we were out of town both used it extensively with no issues. Come Monday & Tuesday when she's back at work, it's same old story - dead by 2pm.
One variable I can see in our case is location.
The wife likes her Hero, but is getting pretty frustrated with the battery life.