Implications of changing a residential sale to a land sale?

[Corey Meyer]

My wife and I are under contract for a great deal with a cash offer on a single family residence.  We are getting it at about 50% of the going rate of price/per square feet in the neighborhood.  The house is livable and was under contract previously with a buyer who had conventional financing.  However inspection didn't pass for bank financing and the sellers chose a lower cash offer from my wife and I.  

my wife and I also own a property on the same block and with our purchase price that it will be seen as damaging to comps.  So the seller wants to change the mls from residential sale to land sale.  Since we are buying in cash it doesnt affect our purchase at all.  We are just wondering if there are any issues that might come up that we aren't aware of before we give the green light. 

Corey