I've owned a Peavey (deep) 2X15 with black widows and a Mesa Boogie RoadReady 2X15. Both were EXCELLENT cabs (Mesa being a little better sounding but the Peavey was great). The Mesa was smaller but WAY heavier. The Peavey was just huge. They both just became too much of a PITA to haul around. I'm totally gassing for a Schroeder 1515+L though.....that thing looks amazing (on paper)!
I love the pants flapping tone of 2X15s....just not the size or weight.
I have a 2X12 Avatar with DeltaLFs. Love this cab....kinda a compromise between a 4X10 and a 2X15.
The Schroeder is a screaming beast. If the performance of my 1215BMF (1 12", 1 15", 1 adjustable tweeter, 44 REAL lbs) is any indication, the 2x15 cab is on its way back in a major way. It's nothing short of amazing how big and clear it sounds.