***only speaking on my local market***
My biggest issue with these 'turnkey' providers is what you're actually being sold. If your ONLY concern is the return on your dollar based upon the figures they are providing, then sure it probably makes sense, but that appears to be the only thing considered in these cases.
I see countless 'turnkey' properties that are sold for 30-50k+ more than the next TRUE comp in the area. Sure you're buying a new house (built with the CHEAPEST material)... but you're buying it in a D class (or worse) area. They typically place sub-par tenants on extended leases and overcharge based on market rent (this all helps those great numbers!).
If you ever look into these properties they are NEVER sold on the market. All deals tend to be sold to investors in large nationwide 'get rich from real estate & networking' groups that they are connected to. Once the deal is done the property is placed on the market with 1 photo, closed out showing 0 days on market and wah-lah they've created their own comp! Now they can justify the ridiculous prices to the next person they are after... that sounds ethical right? Don't worry though, you wouldn't know on the surface because if you pull the taxes you'd never tie it to them as they use countless llc's to protect the cause.
Oddly enough for as large as they are they still have other agents (not related to their group) place the homes on the MLS and then close them out to create said comp. They do own the management side of it as well and have showing/buyers agents (as they are always making offers from their own group) so it's not that they are incapable of listing their own homes.
All of this to say do your research on a true market value. If down the line they press you to sell through them and yet your house never hits the market here's why. It's being re-marketed to other investors in your exclusive real estate group that everyone paid thousands to be apart of and thinks they are getting these great off market deals. Likely they are pushing off you finding out about the true value and the only way for you to not uncover said truth, is to reel another unsuspecting investor in.
Rant over... sorry guys
I'm happy to pull true comps or help you dig into the background on any property.