I guess its also a matter of how high in frequency the SUB plays /contributes .
The lower the freq the more omnidirectional the sound .
The SUB i design also plays into the midrange , acting more like a center channel
Yes, I think some of the speakers we have owned benefited from slightly higher crossover...but that only works if the sub can perform at that level which is where your design is coming from. I suspect the PureLows can do some possibly the Wilson Benesch...and perhaps subs like Von Schweikert where they are presumably designing their subs not just for subterranean performance but for evening out lower bass generally so might possibly include more than just sub 45hz performance.
I've now mated my Alsyvox Carravagio with NAT Audio Transmitter Evo. Direct coupled, singled ended, 80 watt triodes fed direct from an Esoteric DAC.. This was a big upgrade over previous Pilium Hercules with their flagship preamp.