I personally use a Nook Color with CM7. It works decently fast, though I tend to give it a full reboot two or three times a week due to slowdown starting to occur in certain applications that I'm not able to account for (probably just too many games opened). Go to reboot it, and two minutes later, it's fully rebooted and running fantastically. Battery life is around 6 hours with wi-fi blasting all of the time and games being played. It's closer to 8 hours with some light web browsing and primarily reading. I've had no trouble installing files, though, I'm not entirely confident on where to put things such as ebooks. I pretty much just have to find a pdf version and use Adobe Reader, which actually isn't so bad. All in all, I wish I had suggested this to you. For around the same price, it seems a better deal than any, if not all Coby tablets out there.
As for your current problem, I'm not an expert on ICS by any means, nor am I knowledgeable of Coby tablets. I'll just give my input here in case you end up unhappy, and end up going after yet another tablet.