From everything I've read, I'll be checking mine about every 25K miles. I don't expect them to change by much, but I ride mine pretty hard, so it's not unreasonable to expect the valves to eat into the seats enough to put one or two valves slightly out of spec in that time.
I'll do it to keep vibrations down and performance up, more then anything else.
I do need to recant my earlier statement, and agree with Pokey and charles r. I've been wrenching on everything I own for my entire life, and I'm told I'm really good at it (it comes natural to me). I also have a compete shop setup with all the tools I need and a lift, so I tend to forget what others may be working with.
Doing the valve inspection on the C14 is a big job, requiring a place to put all the pieces you remove (and there are a lot of them), in some organized fashion. You also need to be able to leave them like that for a couple of days to a couple of weeks. It requires some tools you may not use very often, or may not have (magnet on a stick is really important, for example). You also need a place to have the bike, with the engine opened up, while you are waiting for shims, or time to work on it. It also helps to have small hands, and very good dexterity.
I certainly would not discourage anyone from tackling this job, in fact just the opposite. I would really encourage them to thoroughly research it from beginning to end, knowing what they are getting into before they start, so they wont suddenly find themselves "in over their heads".
