IF you plan on going back someday, and this is the home you want to move back to, then renting it would be a good idea as long as you estimate that it will cover itself, or preferably, cash flow, which it appears that yours will at @ $2K or so per month (after expenses). 

We sold one for $257k in cash and are holding the other one as a rental.I’m curious about others’ thoughts on build-to-rent (BTR) projects, especially on infill lots.

Seller wants $160,000 cash out which leaves $50,000 in equity for the buyer.I had a taker from CA but he couldn't come up with the cash.I was not aware of anyone that understands that kind of deal.  

Then you can read a more in-depth book like The Book On Rental Property Investing by Brandon Turner or The Unofficial Guide to Real Estate Investing by Spencer Strauss.Here's a guide that teaches you how to analyze a property.https://www.biggerpockets.com/blog/rental-property-cash-flow...Finding deal that cash flow is the easy part.

If I have some cash do you recommend clearing the loan or invest instead for next property with proper planning ? 

You don't want to cash-out refi and then be sitting on cash costing you 7% while you search for a deal.

Purchase price: $417,500 Cash invested: $37,575 We weren't super happy with anything we were seeing on the market, so my husband and I had just started writing letters and looking off-market... until we saw this property.It'd been sitting on the market for months, originally listed around $550,000.

Unless you paid cash?

Purchase price: $80,000 Cash invested: $80,000 This is a reno- adding a 1 bedroom unit to a three family home.

This may kill your cash flow due to high interests rates though. 2.