I've had several models from both brands, but I do feel that Vandersteen is a better speaker. I can't really tell you what to do because you may not have the same taste's as me, but I can give you 1 piece of advice that may help. The one thing about Vandersteen that most people don't get, even some of the people who own them, is how transparent they are. They let you hear more of what your electronics sound like than any other speaker I know of. With a Vandersteen based system, you can usually change what you don't like with electronics.
But you shouldn't take my word on something like this. You're talking about too much money to just guess. If you can, borrow some gear from people you know, or a dealer. It doesn't really matter if its something you would actually buy, or not. Just do it to confirm my comments on the transparency of your Model 5's. If you don't hear things the same way I do, then maybe new speakers would be a better choice.
But you shouldn't take my word on something like this. You're talking about too much money to just guess. If you can, borrow some gear from people you know, or a dealer. It doesn't really matter if its something you would actually buy, or not. Just do it to confirm my comments on the transparency of your Model 5's. If you don't hear things the same way I do, then maybe new speakers would be a better choice.