What would you consider to be the best bang for your buck security system for short term rentals?

A 9–10% cap rate with a 1.6 DSCR is strong, especially using 1031 equity.

For example I offer a limited service product in FL at 10% and I can show I am beating the market 10-12% here through marketing on 15+ channels (Abnb, VRBO, Google Vacation Rentals, BDC, Cap 1 Travel, Marriott Homes & Villas, etc).

Cap ex and random maintenance seems to suck away all the profits.

I would not waive inspections and escalation clauses are great, don't put a cap (because if it goes too high then you just walk away) and leave the appraisal contingency. 

They both handle cap table and record keeping.

Even $50k trapped and I have a 200% short term return from the value added above alone.if I have $0 invested, even a couple hundred a month of real cash flow (after properly allocating for all expenses including future cap ex) produces a great return.i suspect there is no bigger factor in the return than the value added and this is because the higher the value added, the less money gets trapped in the property.  

Do make sure their Federal Lending Cap is big enough for your growth and Scaling plans. 

They also have a lower ROI/bang-for-your-buck than aesthetic upgrades that are easier to see and enjoy.

For the HOA, you'll want to review meeting minutes, financials, and see if there's a rental cap because ideally you'll want to rent out post-move out or if there's a spare bedroom, be able to rent that.