This is a good match, especially if the designer is willing to get their hands dirty in the code, or go out and do sales, at least a little. Otherwise, I think designers will be sitting on their thumbs a lot once most of the initial design is in place.

That's not to say I don't value what they do, just that it seems their work is mostly front-loaded. Once you're launched and the design is fairly stable, the designer needs to be willing to switch hats and pick up slack where they can.

I think that a designer can design as much as a developer can develop on a product. The best designs are the ones that are iterated and iterated upon. A designers work is never done, etc.

All founders should switch hats! :)