I ran 31's and 4.10's for a couple years. I actually really liked that combo. Now I'm running 33's and the stock 4.10's until I have the money to re gear. It's definitely a DOG at the moment. But it Looks good! lol
If you run 31's you are running about 10% over stock gearing, if you are still running stock 4.10's. Personally, like I mentioned, I really liked that combo. It still had most of the bottom end of stock, but tached a little lower at speed. And it still climbed hills decent. I'm looking at going to 4.88s with my 33's. But now that it's not my daily driver, I'm thinking 5.29's make more sense.
Good Luck!
Grant