I also go to school in Ontario, and have my car insured on BC plates. Here's the scoop:
1) You must be a full time student, and be prepared to prove it if you ever have to make a claim. I'm in the middle of making a claim right now (fucking vandals!!!). I had to fax a copy of my Verification of Enrolment and proof that I was a BC resident when I insured the car (I sent a copy of my credit card statement showing that I drove from Victoria to Ontario).
2) Your rates, whatever they are, will double. Going out of province makes you region Z, and whatever your base rate is goes up by 2X. In my case, that was still $1500 cheaper than the lowest quote I got in Ontario!
3) You may need proof that Ontario is okay with you running BC plates. The rep I used asked me for the name of the person I talked to - I said I had no idea, and that was that. But apparently there is a place where they fill in whether the authority in the destination is all right with out of province plates. FWIW, my understanding is that Ontario is fine with out of province plates as long as you're a full time student and your permanent residence is the same as your plates. If you're in a university town like London or Kingston, you should be fine.
4) As far as making a claim goes, if you ever have to, ICBC has an "out of province" department you deal with. I had to get a couple estimates, as well as the aforementioned Verification of Enrolment, and send it all off to my agent. Still waiting to hear from him, but once my claim is approved I'll get the work done, and ICBC sends a co-pay cheque to the shop which I have to sign before the shop gets paid.
If you have any other questions, feel free to email me - I don't check RS much anymore. My email is
demosthenesx@gmail.com.