BB7 calipers are going to run you around $120, discs will be another $50. I don't know that mechanical discs will really perform any better than a properly set-up cantilever set will, but if you ride in lots of wet/muddy conditions (like CX racing) it might be worth it. I would definitely try this out before buying new disc-hub wheels. Disc hubs with QR/130mm spacing are an oddity these days. If you stick with rim brakes, you will have a lot more options for new wheels.

I've also gone down the road of trying out mini-v's. I had the TRP CX9's for a few years on my old CX bike. They're really powerful, but the modulation is terrible, the levers feel really mushy, and the pads have to be run super close to the rims so they do not work well in mud and were constantly rubbing.

I eventually replaced them with a set of Avid Shorty Ultimates, which have been (by far) the best cantilever brakes I've ever used.