Ok thanks for the heads up man. I'll look into upgrading her phone to that soon. You havent noticed much of a battery change?
Yes, I have noticed a battery change... for the better! --- The reason Kit-Kat runs so well on this phone (as well as on the 1st generation Kindle Fire I flashed) is because it is optimized and designed not to be a memory, processor, and general resource hog, more so than previous versions of the Android OS. I'm not "technie" enough to explain why, but I believe the goal is to be able to deliver a faster, smoother operational experience, even on lower end devices. Since the E4GT is now a "lower end device", due to its vintage, processor, and memory, it's not surprising that Kit-Kat works so well on it.
If you don't want to get so adventurous with the Kit-Kat upgrade, I would still recommend skipping Ginger Bread and Ice Cream Sandwhich, and updating to Jelly Bean. While not as great as Kit-Kat, Jelly Bean runs quite well on this phone. It was also the last official release by Samsung and Sprint for this device. You can find the update file (no OTA) in Samsung's archives. However, if you want be a little bit adventurous and get a very easy taste of rooting and flashing, search this forum and XDA for the "Odin One-Click Stock Rooted GB27 ROM" for the Sprint Samsung Epic 4G Touch (D710). This is truly a super-simple method to upgraded to stock Jelly Bean and get Rooted all with literally One-Click. --- Good Luck!