I love my Model M (I even still have a few reserves I bought on eBay many years ago, haha) but for the last couple years I've begun having problems with pain in my hands after only a few minutes of typing. It's not my wrist, but more the joints & knuckles of my hands (I'm 33 now, so I guess it's not out of the ordinary after a lifetime of typing).
I'm not nearly as fast as you as you are, but I've been able to easily clear 100wpm for just about all of my adult life and I've done a lot of work behind the computer so my hands have racked up a lot of mileage. I'm three years older than you and it wasn't until about five years ago that my hands first started to give me problems. I think all the high speed typing combined with long hours of use finally caught up to me.
It got back enough in the past couple of years that I started to use speech recognition software because I could no longer sustain extended typing without being in pain. I'm a programmer so I'd only use my hands to code because that is really hard to do with speech recognition and for everything else, speech recognition did most of the composing.
That was until I got my hands on a Filco with Cherry Browns. I discovered this board around a year ago and got acquainted with all these great keyboards and got to try a lot of them out. I'm not totally pain free, but I can handle any normal day's wear and tear without discomfort and I'm not going to bed wondering how much longer my hands will hold out.
I'm typing this on a Realforce103 right now. I just got it yesterday and I can't say for sure yet if this is going to dethrone the Browns, but my general feeling is that this might be my new favorite switch and board. Even though the key weighting is on par with the Browns, it really feels different and it's taking some adjusting for me to get used to them. It's the same process I went through when I first started using the Browns. Just the subtle difference in feel is enough to throw you off for a while, but judging from your Typeracer video, you'll adjust in time.
Although it seems sensible that you might like the Cherry blue switches because there's some click to them like your Model M, it's a totally different kind of click and if you're doing 175wpm on Typeracer, you're probably bottoming out and that'll be all the tactile feedback you need. The "click" of the blues is also more of a "tic" rather than a clicking sound. Also with me, my hands feel the effect of typing on Blues more. My hands do get sore after a normal day even though the force differential between the Browns and Blues don't appear to be that great.
Like the rest of here, you'll just have to try out as many as you can to see what suits you best. I wasn't trying to steer you away from the Blues. I just wanted to point out that picking the Blues because they also click might be a flawed approach.
I've recently discovered a few typing speed sites (like typeracer) & also have a video of me typing there @
http://www.youtube.com/watch?v=rjAB7RxfC90
If you hands are hurting, wean yourself! Defending your spot on Typeracer isn't going to do your hands any wonders.
I note this because on the aforementioned cheap POS keyboard
Around here, POS stands for "Point of Sale."