I assume you're interested in this because it's a racing thing. You should know that racecars use special racing transmissions, like Jerichos, which are much more robust than your stock s2k transmission. And clutchless shifting is hard on *them*...

 

Jericos have square shouldered gears (hence the loud whine) and dog rings instead of syncros which are thrown away after a few hundred miles of clutchless shifting.

So, if frequent tranny rebuilds are going to be part of your regular S2000 maintenence, enjoy your clutchless shifting. Even if you are good at it, it's hell on your transmission.