I am no accountant, but I prefer to keep my capital gain investments outside RRSP's. The biggest reason I do this is because any gains inside an RRSP are considered as income for tax purposes, which means that you are paying your highest marginal rate when you cash out your RRSP. In fact you are paying tax on both the initial investment as well as the gains. Yes you can defer the tax payments on the initial investment
Even if you wait until retirement you may be forced to convert it to an RRIF which means that you may have to pull out more than you actually need, causing you to pay tax on money that you don't need and possibly getting your gov't pension clawed back.
So I prefer to keep only income bearing investments inside RRSP's and capital gains outside. The capital gains tax has historically been a fraction of the marginal rate. Also if you are of the "buy and hold" strategy, then you are not paying taxes on the gains until you cash out, which could be in your retirement if you can hold'em long enough.
There are probably still times when it might be beneficial to hold capital gains inside an RRSP, you should always do your due diligence and learn as much as you can.
www.taxtips.ca is a great website for Canadians.
Cheers,
LW