Of course your clients want you to handle it for them - they trust you and they do NOT understand what it takes to be a PM either.

Since they all follow the same guidelines, and it was an unbiased 3rd party, there is significantly higher chance your refi numbers will come out closer to what was expected than just trusting Realtor opinions (after all - banks don't hire them for an unbiased evaluation of homes prior to lending). 

I've never been there, but I've put a lot of trust and faith into good property managers.

But the toughest thing is to find one that you trust and that will do a good job.

I was told I made a mistake by creating an LLC and was told I should have put my properties in a land trust.

He has done some spec builds and some flips and I trust that he will make me whole if things go south.

For example, flipping vs buy-n-hold, 2 very different operations and taxation implications, or say a person has a trust aspect, partners, foreign LLP's involving interstate aspects, etc etc etc. 

Along the way I have learned to trust the gut. 

If people I know and trust have had success with a GC, then it's more likely they're good. 

Your question needs to be about what properties give you the most profit and not about the insignificant difference concerning the amount of time and labor in regards to larger or smaller properties.As for turnkey properties, that is a huge subject and don't ever trust someone else to do your math or manage your properties.