Not really. I have a 21SF. Most of the people I hear from just say holding the normal 21 is like holding a brick.
Along the ammo line, don't shoot a whole lot of +P ammo out of it, either. That's for any Glock, really. It's not rated for it, and while it can take some, it's not in your best interest to do it often. Like hand loads and lead rounds, Glock doesn't advise it. Like I said, you can, but I wouldn't make it a habit.