If you are having problems with the power button and it is giving you difficulty, then it is best to get a replacement. The power button could end up not working. As for the replacement not having GB, it has been pulled because of issues so don't know what to tell you about that. If you want to chance it, then keep your original device.. As for as the data, you can set the phone to CDMA and it won't toggle. If you see it is using 3G more than the 4G then use the 3G. Setting it to CDMA will help improve the battery because you won't be toggling. Allowing the phone to choose the data, then it will use the battery more.
I have 4G in the city, but not in my home area. The 3G works fast for me, I don't care about not using the 4G. I would rather not have the battery issues.
If you decide to keep your original, just refuse the package from Verizon and if you need to get a replacement, you can still get one later on. It is up to you. Personally, I think you should take the replacement. Having a defective power button wouldn't be advisable. Verizon will release the gingerbread again when they get the bugs fixed. It is still a great device even without the gingerbread.