I just bought a Seedhouse SL 3 for the wife and me, which I've only had time to try it one night at the local park.
At 3lb-15oz (confirmed) it is light. It has a ton of floor space and has a reasonably peaked roof which I think would shed some light snow (but haven't tested). The SL 3 has an additional middle cross pole that would help support any snow that stuck. Don't get me wrong, I would not categorize the SL 3 as a robust, four season tent, but it could extend your three seasons, particularly if you can camp somewhat sheltered below the treeline.
Otherwise, this is a wonderful summer tent as the inner is all mesh and I've figured out a way to lash the rolled-up fly onto the top pole, which runs the length of the tent, with a strip of silnylon and a slip knot. If rain starts, I can quickly release the lashes and the fly rolls down the sides like a window shade!
Like most all double wall tents, this would be a pain to set up while raining as the inner tent must be set up first but, this is the only drawback that I can see.
As I like winter camping, I also have a Hex 3 which I have total confidence in during the "fourth" season but wouldn't want to even think of using it in hot, humid summer. .... So much for the universal tent! :)