Start with BiggerPockets Ultimate Beginners Guide (free).

but with that said, it seems like you're assuming OP will be able to have a high performing / top performing STR (which i think we would all agree would beat unleveraged market returns.) 

Come to think of it, though, I can't imagine why they wouldn't let me perform one just to understand how much I can offer.  

He even agreed to selling me one of his since it’s already performing and ready to go.

I would encourage you to read this beginners guide from BiggerPockets, it's a good bit of information so pick and choose what you want to read or read it all.

If your current photos are performing well, you don’t need to change them often—just refresh when there’s something new to show!

Owners mistakenly ASSUME all PMCs offer the exact SAME SERVICES and PERFORM those services EXACTLY THE SAME WAY, so price is the only differentiator – so, they often select the first PMC they call or that calls them back!

Any one have any feedback on them and/or their performance? 

I’ve reviewed a number of theses DST’s across numerous asset classes  and there performance /returns are generally fairly low and unimpressive. 

Cold calling is already such a poor-performing strategy. the ONE thing good about cold calling is that you are talking to a HUMAN, building rapport, and asking and answering questions.Now that ONE good thing about it is taken away...Like David above me, no experience, and it would indeed be interesting to see how it does, but that doesn't take away from what I mentioned above.