My players use the MIC extensively, and I try to use as many MIC items as possible in loot. It's just entertaining to see them come up with some new use or whatnot. Keeps things from becoming stagnant.
I don't think I've seen any game-breaker in the MIC, though there are far too many for me to be sure. Many things such as healing belts seem cheap, but work out fine in game. Generally, the DMG items are far less well balanced speaking globally. There are items everyone needs to have, and items no one will ever buy, always selling them (to some insane buyer who wants them

).
Hellcat gauntlets aren't that powerful. Sure, they're cheap - but a lesser rod of empower can empower a fireball to 15d6 damage by 10 character level, to all affected creatures. Hellcat gauntlets, by 10 character level, only add 5d6 slashing damage to a spell which must be 5th level - but that's unhandy, since you have far few fifth level slots. It also only applies to one opponent, and to spells with a Target: line. Finally, damage reduction applies, which is problematic, since many many creatures have damage reduction/magic by that level.
I'd say the hellcat gauntlets aren't overpowered compared to the rod of empower, all things (such as price) considered.
A better strategy, if you find the power creep objectionable, is to allow MIC in its entirety, but to reduce treasure across the board by 10-50%. You'll still have the enhanced selection and fun, but will be less dependant on magic items. This will, of course, shift balance toward buffers and classes which don't require magic items to function (such as the druid), but I'd prefer that to the DMG's boring, badly balanced fare.