Because you've been using a DIY UQ, I recommend not buying a hammock with Built-In quilt (Superior Hammocks) until you've used a commercial quilt with of a specific Temperature Rating. For example, though a quilt I use is rated at 20°, I start to feel chilly when it the temperature drops below 30°. I'm not saying the UQ isn't up to parr spec-wise. It could be just fine at 20° for someone else. But for ME, I've found I'm more comfortable if I have about a 10° cushion between the rating and the actual temperature. I'm reminded of that every time I use a 20° and the temperatures drop to 24°.

So, you are looking for a built-in UQ at 40°. Are you anticipating that you'll be comfortable at 45°?

Of course one vendor's 40° UQ won't be exactly like another's. But in general, a 40° is a 40°. If you anticipate using the hammock at 50° and above, most likely it would be fine. But, again, because you've been using one you made yourself, t'were I you, I'd try to get some experience with a commercial UQ's at specific rating to make sure 40° will work for you at the temperatures you anticipate.