Its just a different approach to the same business.

I think it works for a lady who doesn't want to think of herself as a "working gal".

I'm sure you've come across some SBs that  are on some of our favorite hooker advertising sites.

price difference, the quality has to still be there, too.  I don't like paying professional rates for amateur service, and just giving me more time is not going to make up for the lack of skills.  At my age, I'm lucky to get three pops in on an overnighter in 12 hours, so I don't need to spend that much time with her when the sex is not as good.  I also don't like the drama that often comes with SB "relationships".  With a professional, its just a transaction, not a relationship, as you also note.  If I want a long-term relationship, I will just find a civvie girl, or be a real-life outside boyfriend to a hooker.  SB "relationships" I have had rarely last more than two months because of the diminishing interest in the amateur service on my part.  I have been boyfriend to working girls who have managed to keep me interested for almost a year.  

The SB market is supply rich, the escort market is demand rich, provided you live someplace close to a college and aren't otherwise in a pussy desert. That's where the price disparity is coming from. The services offered are different, but I wouldn't call one better than the other by any stretch of the imagination.

SB's are more work to manage, but they're way cheaper. I don't agree with the sentiment that SB's aren't as good in bed, and I'd hazard to say it's much less that they're bad in bed and more that the guy's complaining about them aren't good in bed, and/or are generally unpleasant so their SB's are more just in it for the money and aren't putting in much effort. If you're capable of not being a slob and know how to show a woman a good time in bed, you'll find that even the pros are more satisfying, and the SB's aren't really that different than the pros.  

Personally, SB's are alot of fun, but, I'll qualify that with the fact that I really do enjoy being around women. If someone just wants to scratch an itch and doesn't care much for female companionship outside of the bedroom, they're probably much better suited to sticking with the pros, or, like damn, get some therapy and figure that shit out.