Looking for general reviews of the various PS agencies out there.  I know of Tryst Agency, Alluring Intros, and Pornstar Companions.

I used Tryst Agency once late last year and they did a great job confirming date, time, location, testing, and other details. I only used them once for UTR gal but definitely plan to use them again. They even sent me a nice thank you text and email after the event.

Not sure if still around but Hetera was really good to me

This sort of question was asked over on the Escort Access board a few weeks ago.
I know that people will for the most part always try and book directly with the model if possible  
I feel though that Agencies help make things slightly easier (if done correctly) by making communication smooth, answering questions and holding people accountable.  
Yes we take deposits to help secure bookings but I have no issues returning deposits if things don't work out
or applying that deposit to someone else or a credit for later use.
Making sure that things go well and you the client are connected with someone that makes your experience amazing is the job of the agency. Holding the model accountable is very important as well.
I wont work with models that are continuously flakey or have poor communication.  
I do my very best to make sure things go smoothly for all parties

You've been great with any email I've sent you!!!  The rate I was quoted for the lady inquired about went up a bit from when I first asked, and for me, unfortunately, put me out of my comfort zone.  A good agency is a wonderful bridge between a gentleman and their fantasy, and you provide that bridge!!!