Big Swing is the hybrid of macrophylla with sagittata that was sold at Maymont and the Baltimore Herb Festival. It does set seed pretty well, and I would suspect that the F2 seedlings will vary all over the place. I would not assume that the sagittata-looking forms would also be weak growers like the parent they resemble. There are now three forms of macrophylla and two of sagittata going around the US, Britain, and Australia. Expect some interesting forms to come out.

You make a good point and so if there are any seeds left I will order them and see what happens. It might be fun to select for strong growing sagittata forms over a few seasons. The parent hybrid has certainly received some very favorable comments in the past year or two.