I had no issues mounting the Helmet Guardian on my 06. You will have to take the round reflectors off, but no big deal. Yes, the helmets hit the exhaust but I solved that issue. Go to any motorcycle shop and they will have a set of metal helmet extensions for locks. These are used alot on sport bikes where the helmet lock is a hook under the seat. Its always hard to get your D rings on the hook and then get the seat back on. These extensions work for that. For the helmet Guardian, it allows the helmet to hang lower, below the exhaust.
As far as re-keying the locks, not a big deal to me because I already have other keys to carry with me for my Xenia disc lock, my Kryptonite cable lock. Get a two piece key chain that allows you to put your ignition key on one ring and the other keys on the other ring. When you go to start the bike, disconnect the one key ring from the other.
It helps to have experience from a sport bike, where you have NO storage room whatsoever. Sometimes you have to get creative.