I know the generic arguments on this topic but need a steer from a grown up who has been there and done this in practice.
I just bought a Barefaced Retro 210 off Lozz. It's rated at 12 ohms. I am running it with a Markbass LM2 which technically kicks out 500w @ 4ohms. With the cab in its current config apparently the head only puts out about 200 of those 500w.
I don't want or need another cab, and have bought a BF 12>4ohm conversion kit to unleash all those foaming, effervescing extra watts . But in your view, for a blues band playing in small to medium size venues (band hall type size), is it necessary to fit it? Should I leave well alone at 12 ohm?