We had pondered switching the MU and Fighter XP charts, but we never got around to it. I would do it now though if another campaign were getting set up. Fighters, to us, felt incredibly flat once you hit name level. No longer getting to roll a d10 for hp felt like losing half the class. Coupled with slow advancement, it was hard to feel excited about them. Getting access to a new spell level (for any spellcaster) was huge. The two extra HD for the MU is not very relevant IMO - it comes out to another 3 hp after two levels. Giving it to the fighter feels more meaningful. Not to mention that MU's get some of the best magic items at the higher levels as well.
The weakness of the MU at early levels didn't bother us because after one adventure, you were out of 1st level and the thief was practically at 3rd. We gave XP for treasure though per the RAW. A lot of people didn't do that, but unless you're inflating the other XP numbers, it will mean that you're stuck at low levels 2-3 times longer than you're supposed to be. That makes the low level MU a lot more painful.
The weakness of the MU at early levels didn't bother us because after one adventure, you were out of 1st level and the thief was practically at 3rd. We gave XP for treasure though per the RAW. A lot of people didn't do that, but unless you're inflating the other XP numbers, it will mean that you're stuck at low levels 2-3 times longer than you're supposed to be. That makes the low level MU a lot more painful.
