Actually, I think your real problem was that your "set" method originally took the entire SelectItem as a parameter. It should have taken a variable of the enum type.
You can create a SelectItem sequence that consists of (enum, String) pairs and I do it sometimes. You just have to do it using the proper set/get method signatures. But converting the enum to its string equivalents will work.
Customer surveys are for companies who didn't pay proper attention to begin with.