I really don't like dealing with gas bike or king's but those are tempting at that price.... the things to watch out for with mag wheels are the bearing races inside the wheel... if they're not interchangeable with something and you get a scratch or gouge on them it's game over for that wheel.
Speaking from back in my BMX days, a lot of us used mag wheels because of their durability but I've cracked 2 rear bearing races and both times there was nothing to do to fix them but to replace the wheel. The bearing races need to be made from a rather hard steel alloy and we used to jump the bikes a lot as well as any and every other stunt we could think up and it was not uncommon to be riding home and one of us feeling a slight roughness coming from a wheel, we would flip the bike upside down and crank the pedals to get the wheel spinning then listen for it or feel for it by pressing our hands on the frame close to the spinning wheel, then baby the bike to my house or another friend's house who had a garage full of tools. Sometimes it was just the bearing losing it's adjustment or lack of proper lube, but other times we would try and adjust the cones which made it feel worse, then when taking the balls out and cleaning up the outer race you would see a lot of little cracks all the way around the bearing race (this would happen a lot with the coaster brakes) . We would put the bike back together best we could and next time we saw that bike out riding with us it usually had a new rear wheel. The spoke rims tended to withstand the abuse of jumping better since the spokes offered some shock absorbing ability, not much, but probably just enough flex to help prevent cracking the bearing race, the mag wheels send All the shock to the axle and bearing so these were always either losing their adjustment, getting flat spots on the balls, or cracking the outer races. Sometimes we would find a nick on one of the cones when repairing a bike which just meant replace that cone, but when it cracked the bearing race it meant get a new wheel.
other than jumping or riding on really rough trails or roads, adjusting the cones way too tight can cause a race to crack and there were a few who did just that when trying to seat their bearings at their own home without one of us who knew what we were doing watching or helping...
This was really common with the Lester mags, not so much of a problem with Motomags or the nylon mags.
I guess with a 26 inch or larger rim and no jumping or hitting pot holes at high speed etc, they wouldn't have as much of this problem, especially on a street ridden bike and may not be a problem on a dirt ridden bike if it has suspension.
