I rode Y-Foil 66 for about 8 years. A family friend practically gave it to me in 2000. In think it was a 1997 model. Threaded headset. Ultegra 9 speed. I think the blue with silver decals/lettering looked really good.
I liked it, though the fit was a little off, so with the high, shortish stem, it lost a bit of its looks.
The seat mast did what it was supposed to do and it was a smooth ride from a butt’s perspective. Fork was not as compliant as some nicer CF forks I’ve tried since. BB and stays seemed stiff under pedaling.
I have read that the fork is on the long side (thus hard to upgrade) because trek had plans to offer a short travel suspension fork with it. I never measured my fork to confirm this.
Ultimately, it was not the type of bike that I wanted (race bike). I wanted something that could take bigger tires, more water bottles, and a rack.
Seemed like a good experiment, but with the UCI banning it from road races, it was doomed.