I have a Ti fork built by TiCycles Fabrication on my 1993 Merlin Extralight. It was originally spec'ed for my 1997 Serotta Legend, and I had it on that bike for a short time. It was a perfect match for the Legend, but unfortunately that bike was destroyed in a car crash (the fork survived undamaged). The fork cost $1100…!! That's right. In fact, the Merlin Extralight frame I bought as a replacement for the Serotta (after a lengthy search for a frame with the exact same head tube length) was cheaper than the fork. I guess when you spend that much on a Ti fork, you'd better put it to use. That being said, I have ridden over 10K miles on the new frame and fork and love them. The fork is incredibly durable, and I've had no issues at all with fork flex. It looks beautiful with a Ti frame, and I can't say I've ever seen or ever expect to see another bike quite like it.
Pros: Looks awesome, highly durable, no flex problems, custom dimensions.
Cons: PRICE!, not aero (round tubes), have to order it and wait for 3 months.