I just now noticed how you started the thread='so, it boils down to 3/4 versus full then'
I thought I'd point out that there are even more variants to be had. Some of the cottages (HG for one) will make exactly what you want.
ON the Roan Higher Colder Hang (8F) I was more than cozy in a PLUQ (partial length underquilt) but it wasn't a 2/3s or 3/4s, it was a 5/6....no longer made by Leighlo. We call it the 5/50, 5 feet long 50 inches wide and rated to 0F. Said all of this just so you know that you dont have to be in the cookie mold if you don't want.
One more thing since you are new to hanging in cooler temps, never forget the thin ccf pads (that as you know can help if you are above treeline and gTg). You'd be surprised how much temp range a 1/8 inch thick pad can add.