I tried both metal and plastic canisters, but always liked the metal more. I used to load them the same way, but the film in plastic canisters for some unexplained reason was very hard to pull once in camera. Especially towards the end. I never had the cover to pop out, unless you abuse, force or drop the canister. As for reuse, I used them about 5 times, and they still look like new. Of course, cleanliness is a must, keep out of dust.
Bulk loading can be very economical and not that hard to do, once you find your way. Whats nice about it is that you can load as many frames as you wish, handy when testing film or just when experimenting. But I know that some people wouldn't be caught dead doing it.
There was a similar topic today in (there was a url link here which no longer exists) thread, it might help as well
Metod