we actually tryed almost the same thing, except we doubled the ranges you needed to gain levels *1000 to become level 1, 2000 level 2, 6000 level 3, etc*
Didn't work. the players grew restless, and wanted new abilities, and even though the fights were hard and more thinking and originality had to be thought out, the party had to constantly rest, and started completely avoiding fights that would gain experience, and started asking me for larger story awards 'which i was giving'. Stick to the current system, munchkiny experience awards are alright sometimes.