I think what I'm trying inarticulately to get at is whether it really matters to ride a bike that is much better than you are in a sort of 'there are only so many great bikes in the world and should a great one be wasted on you' way.
Do you mean to say that in some way you might be undeserving of the bike? I reckon that might be true if you were a 'rich prat' who never used it for the purpose it was designed for. To me the bottom line is that you have paid for the bike, which unless you are rich (not necessarily a prat!) you will have had to work for. So you should feel as though you have 'earned' the bike and are therefore deserving of it. And since you obviously ride (and well if other posts are anything to go by) then that marks you out as a (retro)biker, hence not a prat!
QED - case closed!