If they could get a good defenseman for JVR, I'd rather go that route and play Kapanen every day. I'd rather not trade Kapanen at this point, but that may depend on how management feels the younger defense prospects (Dermott, Nielsen, Rosen) are progressing. Are any of them capable of stepping in and improving the defense next year? I don't ever see the Marlies so I have no idea.
Even with a defensive upgrade, I don't think this team is ready to be a serious contender...yet. So I'd rather not move one of our best offensive prospects especially when it's not clear what else is happening up front with JVR, Bozak, Komarov. But at some point, it will have to be considered.
(edit to add - I think I had misread your post, for some reason I thought you were advocating trading Kapanen but now I realize that's not what you were saying. Too much New Years for me, I guess!)