Yep, but if O/P's guitarist is using 150w, none of the figures above matter?
I think the problem is that plenty of combos will go loud - i.e., could go even louder - but in my experience most will not sound great doing so. Even the best bass combo ever made - Mesa Walkabout 12 - can struggle when things get messy. OK, it can compete in most situations, but it may not compete in the optimal way (and as far as I'm concerned I don't want my amp to compete I want it to win!). So, I moved from the Walkabout combo which was struggling at times, to the Walkabout head with two Bag End 12 and voila, still an easy load in/out, but both the volume and the tone I was after 👍