Belt tails are MUCH better than motor tails. I don't even recommend getting any CP heli with a motor driven tail, just not worth the trouble.

No CP heli is going to be durable enough to withstand a crash without needing repair. You'll have to expect to replace main blades, main shaft, feathering shaft and possibly servo gears (unless you get metal gear servos), landing gear and tail boom at the least.

The 250 size is going to be very difficult to learn on. Bigger is more stable and CP is going to be very different from your msr. It's going to take a lot of patience and practice.

I think the blade 400 is going to be your best bet out of those, but a lot of people seem to feel that the electronics need to be upgraded.

You might be able to do a trex450 or clone within your budget, you might want to look into that, but you'll have to do some research. Will probably be much more stable than anything your considering and last you much longer.

Considering the school situation, you might want to reconsider whether now is a good time to step up to CP. Like I said, it's quite a bit different from coaxial and fixed pitch and will need time and patience to learn.