OP here. The subs arrived today and so far so good. I’ve been fiddling for an hour or two, but most of the adjustments don’t seem to make much difference one way or the other, other than the low crossover point and the volume.
My system definitely sounds fuller and richer, but I wish the lower bass notes were crisper and more well formed. Probably, I need to do more fiddling to get that, or perhaps it’s just the nature of my room and where I need to put the subs.
Anyway, there’s my report.