I had great success with Orion Lipos, if it wasnt for the price they would be one of my first choices.

I only run soft case packs now, so in comparison, if your hard case packs have swollen to the point it is expanding the case, I would suspect they are swollen much more than what I would call "minor swelling." I have one cheapo pack that grows a little in size every run for the last year. But, it always comes back to firm after resting, the cells balance perfectly, and the punch is still adequate. I think this is the exception to the rule though, I think that unless you are willing to have a potential problem, you should discontinue use of any pack that shows swelling.

As for why it happened, its very hard to say without knowing your habits regarding charging or using it. If you balance charge the pack frequently, dont over-discharge it, and store it at appropriate capacity levels, it may have just been its time.