If they blackmailed/Identity thefted you they'd have no business. They're not shady like Perfection Models, they're fine. They can be a bit brusque/rude sometimes, but they're all business and they're legit. And it's not just them, a lot of the agencies and even indie providers are doing this now. Decide what your comfort level is and then do it or don't.

I had a good experience with them.  
The booker isn’t particularly warm and fuzzy (all business) but she got the appointment set up efficiently, so that’s the important thing.  
The photo ID thing seems To be becoming more common. But at least with PC it’s legit.

...providing all this personal information if you have a few references from providers you've seen recently.

with this level of screening. I've been on this and several other boards for years.  Seen many many porn stars and used TLC up until a few years ago.  Adonia never used this level of screening.  IMO this is a recipe for disaster and frankly I would really use my big head in this case.
I'm heading to Vegas for ten days in October and was hoping to see a couple of girls who are on their list.  Do they accept references from East Coast Agencies? Indy Providers? White list references here from porn stars?  
And....are there alternatives to PC now....I believe there are other agencies shilling for porn stars...any thoughts?

What exactly are you afraid of? Sorry, but this is becoming more and more common. And if Adonia were so great, she wouldn't be in jail now.

Adonia is in jail?  My understanding is that she has been indicted but is out on bail.  I don't believe that the trial date has been set.

alluring is another agency. skeptical that everyone they have listed is available but they have a nice list.