As a rental, even on the low side, figuring $2,000/mo for a $100k investment in Greenwich, ain't too shabby IMO. 

Off street parking, low maintenance, open floor plan on main level, central-air, fenced rear yard.

I anticipate that if I sold, I could probably get on the low side $500K and on the upside maybe $550K/$600K.

Now the tax assessments can vary widely, I’ve seen land value as low as 3% and as high as 65%!

The reason for the seller's willingness to discount that much in today's climate, from what info I have so far, is due to the extremely low rate on the modified loan (less than 2%, recast for a new 30 year term).So due to the rate, even at 50% of UPB, the return on my investment would be around 4% after considering servicing fees, etc., which is not nearly enough to interest me in this deal, considering the risks of borrower re-default, etc. 

You'll probably need to go with a low down payment program like FHA. 

We are also losing out to cash offers since our price point is low (under $150,000 in south Florida).

I see similar price reductions in Palo Alto, where I live. 

The plan is to only go for about 1 year.My thought is that I would like to have about 3 houses rented when we move to Central America, but some say refinancing out of such a low interest mortgage is not a good option... but that's why I'm posting to get your thoughts.

I would be very leery of doing this size deal long distance with those low rents.