i tried them for the first time about a year ago and quickly adopted them as my new condom of choice.
a little roomier in the top half made them much more comfortable, less restrictive and, at times, allowed me to forget that i was wearing anything at all...
however, during a recent trip to miami i ended up hooking up with a english/columbian girl and we had quite a bit of vigorous sex over two nights.
we ended up using 8 or 9 condoms and 3 of them broke.
had never experienced that with the ecstasy magnums and, for the most part, regular condoms.
there was one girl in college that i used regular magnums with and they frequently broke.
considering i have only had a problem with breakage with two girls, it makes me wonder if there was something about the shape of their vagina or the way we moved together that made the condoms break...
fyi, i find that when i'm forced to go with normal sized condoms there is probably a 50% breakage rate.