I had a hard time with the same decision and haven't tried my choice out yet but I did research for about a month. What I came up with was a Marmot Grid 2P.
It is a 4 season tent that can be pitched in the rain and not get the inside wet. The weight is not much more than a 3 season, about 4 ounces depending on the tent.
Check it out, it received good reviews and will hold up to a snow load and serious rain. Don't get caught in bad gear when it can be prevented.
