I use a BackpackingLight Primaloft TQ in the summer in temps down to the low 50's. At 13 ounces, it's not too bad. Once it get below 50's, I go back to my down. The BPL TQ hasn't had any issues. If it had a bit more Primaloft, I'd use it cooler than I do.
If I was going to buy one TQ, I'd go for the 30 over the 40. That opens up a lot more flexibility and covers more unexpected weather. I wouldn't bother with a 40 TQ until I had my 3 season requirements met.