As McPoyo stated, neither of these are uber powerful or going to cause a problem. The only case where I think a DM would have a problem with it is if he liked destroying equipment on a regular basis (ugh, my current DM), but then you would not want an item familar anyway in this situation.
Ha, there is a third party combo that is really funny and broken with Item Familar. Races of Renown: Plot and Poison has the absorb familar feat. You basically merge with your familar and loss access to its abilities that are not numerical bonuses, but all the numerical bonuses are doubled. It does not say it is destroyed, just subsumed and made part of you. +10% xp sounds like a numerical bonus to me, then you just have to pick the right +bonus magic item.
Mighty fist amulet +10
Belt of Magnifiance +12
I am sure you can think of a few more. Edit: Oh, and all of the bonuses are EX.