I wonder how prevalent that is and what drove that.

They have existed for much longer than that but weren't prevalent enough to warrant attention from the local government. 

Is it statewide Texas soil issue or more prevalent in Dallas?

He lived and worked in an affluent community where FHA and VA loans were not prevalent due to their low loan limits.

An example assignment agreement would be a huge help; double closing is just one approach that seemed fairly prevalent (maybe more so once my buyers list is solidified).  

They seem to be pretty prevalent and with a little sweat you can find yourself a deal from what I've heard.

This of course is within the FHA loan limits of values; it is not as prevalent in the higher end markets, though they too are experiencing some valuation increases.Interest rates being low is only one item, lack of inventory, previous short sale victims now at 3 year mark after short sale, thus qualify for FHA loans again, and many other factors are driving this market and it should continue for a while until the market shows signs to the contrary.

I would still keep an open mind for other parts of the state (i.e. central, western Mass) as I have found that good buys on multi-families are more prevalent.

[ though still an issue, not nearly as prevalent nowadays]  The word that popped into my head was NOT weird.

There are few small multifamilies around locally but single families are much more prevalent.