I would say a few things.
1. RQ is not very class oriented, so just because you are a potent sorcerer doesn't mean you can't be an accomplished spear and shield guy too. This can help with the MP allocation.
2. If the MP situation is a real concern for the style of play you want to encourage in your game world (aka dungeon crawls, multiple encounters per day, etc.) you can always increase the Magic point recovery rate in your world. Maybe half MP recovery every hour, full recovery in two- or whatever works for you and your players.
3. Make the players decide when to conserve. If they know a dungeon crawl is coming they might want to duke it out for the first couple of encounters, saving their MPs for the big toughie that they are searching for. Or you can give them hints and insights (with rolls or without) to help them make these decisions.
EDIT: 4. Also, run a couple of test battles and you will see RQ2 battles don't last that long, 3-5 rounds on average for beginning level characters, so you shouldn't burn that many MPs. Also with the manipulation skill sorcerers don't need to spend tons of MP for a very potent spell, just cast them at the same time, add a couple of manipulations, and boom, a 4MP bomb. Spirit magicians, depending on how many Spirits they release, don't spend that much either, roughly 1MP per spirit. Divine magicians don't spend any MP, but have POW dedicated, so, the don't have as many MPs as they would normally. It's really common magic that eats up the MP's, and that does have to be managed, as it generally doesn't last that long either...
Having said that, I have done it both ways in games I have GMed and I find 2 Encounters per day a good average, with 3-6 hours in between encounters. I have seen stuff on line about using survival and perception rolls to decide the frequency and intensity of encounters. I like that idea and may incorporate it into my games as well. This makes the players more cautious when entering "the ruins they've been searching for" and, I find, hightens the stakes and the tension- especially because a string of bad dice can lead to a nasty PC splatter on the wall. Encourage at least one of the PC's to get some serious healing magic as the bad damage can get really bad really fast. And yes, Sorcerers, as they get powerful, get really powerful. Spirits (as you may have seen in some posts here) and Spirit magicians are potent as well, so be careful with their implementation in your games. They can be lethal against PC's with no skills in the area of spirit magic.
I'm sure you will get loads more good advice on here. Good luck, and Welcome!