I have seen two cases where it went the distance and the buyers successfully sued for specific performance.

Using a HELOC isn't a bad way to go as long as the numbers make sense. 

At the end of the 5 or 7 years, if I keep the property that long, it's rinse, lather, and repeat. 

However, weighing your options and performing due diligence carefully based on your specific circumstances, the property's potential, and your long-term goals.

There are a few that do not have any seasoning requirement on a cash out refinance as long was there was rehab completed on the property.

I have multiple lenders that can do 100% financing for your short-term rehab loans and long-term DSCR cash-out loan options to refinance and hold the property once it has been rehabbed.

Use the HELOC on cash-generating opportunities like flips, then use the cash generated to buy long-term buy and hold investments. 

MTRs fall into the standard long term rental( 30 day +) category and will follow those regulations set for Long term rentals.

Now he has sold the company and is more of a flat rate charge based loosely on how long it takes him to prepare the return.

Not good I think its a good tool for fix and flip and short term holds but not for long term holds if you have not ability to refi or enough equity to sell quickly even if you do and the sellers loan gets called they are still going to get their credit trashed. .