For the record, I've ridden miles and miles with a spare helmet attached. It may cause a little scuffing on the fairing depending on how hard that part of the helmet happens to be (my current one wouldn't do it, but sadly it's usually on my head). But I've never been super picky about scratches here and there, so never bothered me.

 

Peg one: (with key still in hand after pulling from ignition)
1) Turn key
2) Hook helmet
3) Pull key and be on your way

Just one of very few (the only) thing I miss about the f2 compared to the new girl