For example if one partner brings the 20% down payment and the other will do the labor for renovations then what would be a reasonable split be.

This might give a one-time (non-scalable) boost to cash flow, offer multiple value-add options, and allow the house-hacker peace of mind, via the assumed mortgage, in long-term breakeven or positive cash flow in the event that the value-add plans end up not being executed, and/or the person has to move out, and rent by the room or STR become unavailable for some reason at a future date.

There is no reason you couldn’t do the same… so why let them make the money and give up the control?  

Short term it is difficult to make the numbers work, the cost of new construction and the time it takes to zone-plan-build are usually the main reasons why private investors stay clear.

Have done some preliminary research and will do a deep dive, just wanted to see what folks thought of there were any obvious reasons why or why not or any markets similar that I should be considering.

There are a bunch of reasons people sell a property.

This is literally the entire reason these companies exists - to get this stuff right.As for why, I have no idea why there has been an uptick.

I am staying wondering why there is so little information on tax liens,  i read some books on notes and foreclosures but looks like a big secret here... maybe that's the reason... i need to go into this to find out :)

Is there a money back guarantee if for some reason it isn't what you thought you were getting? 

It may be more worthwhile to find someone who has reasonable fees for their service as my two cents.I hope this helps in some way!