The only down side really is losing credibility with the listing agent and seller which affects your agent more than you and isn't the end of the world unless the seller or listing agent is like the #1 agent for investment properties in your area.  

Greg L. brings up a great option for your situation by recommending to seek out local banks to finance the purchase, however, there are few downsides you may encounter with traditional financing.First, based off what you said about the seller, it sounds like he may be reluctant to tie his property up for a month (or more) while your bank goes through its underwriting and closing process.Second, the bank will want to see that the home passes inspection, if its been vacant for over two years, you might have a problem.

Downside is we feel kind of homeless when we return to the States!

The only downside with Penfed is they will limit the number of loans you can do with them 3 NOO plus your primary residence.Feel free to PM me with any questions and happy investing!

He's somewhat pricey though, which seems to be the only downside.

Not saying don't do it, just saying to keep a close eye on the downside risk and make sure you can mitigate it before you get drunk on the upside ROI potential.Finally, as an alternative, consider cash out refinancing the SFH equity and reinvesting that money instead of selling.

The downside is that he can get residential loans, while I'm playing the commercial loan world.

There is no guaranteed absence of downside.

The only downside is your cash-on-cash return is going to be like 2.4%.

For sure, its an upside cap during the lease term, but also a downside risk floor (assuming no default).