You seem to be answering your own question. 
Well, I guess you would be running the risk or misleading him if
you accept the date, but then again, as you said it yourself, its
an opportunity to get to know him informally.
In addition, you won't know for sure whether the guy you fancy
will reciprocate your feelings for him, right?
Since your single, its always better to keep your options open.
I say accept if he asks you and enjoy the date!
