1: consistently better girls (tho I've had a few really hot 141 chicks)
2: you have some idea of what she looks like before you go (tho I keep a few known 141 chicks as backups)
3: I tell the agent in advance (and in Chinese) not to B&S me, so it never happens
2: much more likely to get GFE (BBBJ is not that important to me, and I usually get the DFK and DATY that I really crave)
3: cleaner environment
4: no direct contact with brothel pimps
5: no sleazy brothel lineups
6: privacy
7: no wandering door to door in narrow corridors, or racing guys to a desired 141 girl praying she's not busy
8: getting through to the agent is a hassle, but at least you know when you get to her door, she's available
9: so, all in all, it's much more like meeting a hot chick from your office in a normal hotel for an afternoon fuck
But in deference to the brothel lizards, I have no experience with Mongkok brothels, but the idea turns me off; tho, I do enjoy the large Sauna places in Bangkok - maybe it's because the employees wear suits.