I can't help with the original query, but I owned and ran km150s and I totally see where people are coming from who say they are thin. Or at least light in the bass -- again, depending on your tastes, what you're used to, who you're recording, what you're recording with, etc, etc. AFAICT, this is by design, since Neumann clearly incorporated a noticeable bass roll-off.
It's not that there is no bass, but it isn't going to be too slamming, particularly if you're farther away. I've used the ak50's FOB for Mule at the front drink rail of the Fox in Boulder and they had great bass response. But for most bands taping with the cards at this location, I would've run the bass rolloff on the V3. I've used the ak50's in a number of different small clubs, including FOB, and they sounded great. But if you want to use hypers from far back in larger venues where you'll already be far away from the sub cabinets and thus have a thinner bass to start with while at the show, the ak50's aren't the ticket, to my ears.
Bottom line, for me anyway, is that if you want hypers for a small club that can be chatty or that has bad room sound, the km150s can be great. But if you want hypers for taping from far away in the taperssection in a large venue, you'd want a mic with a flatter low end response curve like the AKG 483 or schoeps mk41.