No interest in racing for me, but I have a killer 20" BMX race bike that I use exclusively for pump track duties. I typically ride the BMX bike at least once a week. It is such a good workout and a great way to dial your lines and technique on the bike. Any mistake that is covered by your suspension and barely inflated knobby tires on the mountain bike will bite you in the ass on the BMX. :rocker:
My girlfiend (who is not into mtb or road biking at all) is loving it as well.
Watching a long time mountain biker take a 20" bmx on their first lap at the track is both amusing and terrifying as they hang on for dear life.