I have seen a couple of lesser known gals, prices reflect that as I just can’t see paying the $$$ for well known stars.  My experiences were good, but nothing different than what a good provider would..well...provide.  

I have seen 12 pornstars in Boston with several of them multiple times.  I think generally they are equal to really good providers.  All of been very humble despite the fanboy attention.  The big plus for me is when you see them in a video and you notice something like a small tattoo or birth mark that you wouldn't have seen except your face was buried there a month ago.  The drawback is they do not act as slutty as they are in videos.  
For four of the pornstars I flew them to Boston from NYC for a multi-hour visit so it was pretty pricey.  They all seem to tour NYC but only a few visit Boston.  Two were worth flying them in and two were not.  The other pornstars that I saw when they toured Boston were generally worth it which was about double a normal provider price.  Nearly all that I have seen have been independent or independent with an assistant.  Only two were arranged through the two big pornstar agencies.  As a heads up, I did not find that either of the agencies provided great communication and/or customer service despite the higher costs and everything.