TBO2 I can only speak from personal experience - and not about asthma specifically. I suffered from seasonal allergic rhinitis (hay fever!) when I joined - kept schtum and continued to self-medicate with Triludan (later
withdrawn due to unfortunate side effect of sudden heart stoppage). After a couple of years I told the medics and have had loads of free drugs ever since. Whilst I was in Germany there was a Harrier pilot I knew who suffered from asthma - he seemed to have no probs with the authorities and said that on the bad days he was OK "once I'd had a blast of 100% 02". It's only anecdotal, but at least it sounds hopeful. As I said - this was all a few years ago - we are far more enlightened now I think. As other posters have said - all you can do is go for it - and you sound far fitter than many of the lard-arses wobbling around the military - although with all that talk of training/racing I'm not sure if you're really aircrew material - can you also drink heavily and act like a 3yr-old? As said previously; once you are in, you can fall apart physically and they'll move heaven and earth to keep you going!
Good luck