My favorite was a hoarder house full of trash that took me six months to turn around, but it turned into a killer deal that earned me a 600% return.

To beat 5.25% mortgage rate....the corresponding, offsetting stock market return would be at least double that...To answer your question requires (1) knowing what risk adjusted return you will be able to earn in the future (2) knowing what interest rates will do in the future.  

Pros: pay off mortgage sooner, one account for everything (all cash + deposits + expenses are paid from the HELOC)Cons: higher interest expense, higher opportunity cost (putting all your cash into the HELOC means you aren't investing it into other things that could yield higher returns)

I plan to continue to invest in a mix of both RE syndication and our own rental properties going forward depending on what makes the most sense and offers the best returns. 

We invest in non performing loans and do some private lending as well.

I will be serving a 10 day notice of non-payment of rent and read partial payments could be accepted without waiving right to terminate if the agreement is made in writing.

Next, and again my current experience is in a different industry but one that's a highly dependent on Google reviews and ratings, I've found that there's always a break-even point where "paying someone off" doesn't provide enough of a return on the payoff. 

As a business owner it's wise to hedge against cash flow and a potential non-paying customer.

If it's a larger debt, I would not offer cash for keys.Yes it is for non payment  

For example I sold 2 properties in the same town that was more than 30 minutes away, just because of the travel time to get there and return.