I think most companies are going to have difficulty supporting a product which is completely different than the one it was designed to work with. If I use Windows Small Business server and remove Exchange and add another 3rd party exchange-type server, they aren't going to work on that email product nor other products which possibly share its database. (this is an example -- I don't know how many products can replace Exchange.
But, as you said, support can be limited, and they are not going to know how to work with an Instance of SQL Standard.
