I have cut a few Avenger wings with this method. SMOOTH is the key word for the template.
another tip is be patient and don't lead the cut at all. That means move the handle slowly with little or no bend in the wire in the direction of movement. A slight (very slight) bend to keep contact with the template is ok. There is a tendancy to pull TO hard to allow faster cutting. Don't do it, just ease it along. Its a little like sawing, you have to let the tool do its job.

CP is spot on about coming out hairy, but then some of his balsa planes are a little "hairy" [>:]