The device is still the same and they still use HTC version of froyo. The carriers don't change anything in the Rom, such as the kernel .or the code which is responsible for battery life... all the fi is add apps and change some of the aesthetics.
I'm sure you have a ton of experience modding phones, and I've gotten my share of early updates myself. But in my experience overall the majority of updates are more stable getting them OTA than getting them early.
There's a reason why many people go through the hassle of going back to stock firmware just so they can get the official upgrade. Not sure if you do the same, but to each their own right?...
