I thinking about a new UQ / TQ combo. Currently using a Kelty Down bag, can't remember it's temp rating, but I think it's a 30 degree ????? I'm a moderate sleeper, not too hot or too cold, maybe a bit more towards cold. I do river rafting trips from late April to early September in Utah, Idaho, Wyoming. Night time temps can vary from 50-60s mid summer to 30s in the shoulder seasons. I'm pretty settled on a 3 Season Incubator (want full length). Now I'm torn between a 3 Season Burrow in 800 fill (rated to 20 degrees), or a Summer Burrow with 900 fill (rated to about 35 degrees). It's only about a $10 difference in price. I'm wondering if, with the warmer UQ, can I get away with the Summer Burrow? Or should I go 3 Seasons all the way to insure adequate warmth no matter what.