I've got them both. The Stingray is a slightly fuller cut (wider legs) and is thicker/warmer. Both are great and I don't notice much of a difference in terms of breathability (both have the same side zips) or waterproofyness. I'm not exactly sure what the fabric is on the stingray - it had goretex XCR on the tags - it feels like some sort of hybrid but it seems plenty waterproof to me; I'll find out this season if that holds up with use. Theoretically the stingray should breath better but I don't notice a difference.
I would say, if you are in a cold area and do mostly lift served get the stingray since they are warmer. If you are more apt to get real wet snow or go touring and heat up then get the minuteman. or if you can try them on, maybe just get whichever fits best.
I say you can't go wrong either way and the deals on those 2 pants can't be beat. I looked for the Theta SKs to replace my minuteman's but then I stumbled on a rediculous deal for the Stingrays (I think I paid like $120) so I just had to pull the trigger. When you detroy a pair a season like me those deals are no-brainers