The cantilever brake straddle cables I have seen seem to come in two varieties: one with the cable carrier an inch or so above the tire and the others about five inches above. I am setting up a mountain bike with new brake cables and am wondering which way I should go.
I am considering using a fork mount cable stop and a Problem Solvers Wide Cable Carrier https://problemsolversbike.com/produc..._cable_carrier on a bike which currently has the long straddle cable, which would necessitate shortening it. I want to change out the handlebar and stem which currently has the cable stop in the stem. I understand that I will need to put in a longer cable housing.
Is there a big difference in braking performance or another consideration which I am missing?

How much leverage do you need? Lower yoke = more, higher yoke = less.

Rain and snow, really hard brake pads, and rolled steel rims require more leverage. The wide problem solvers yokes help with rear brake clearance on small frames where more leverage is needed. It may also come it handy for the fork mounted cable stop. Straddle cables are cheap enough that I start with a 90° angle and go higher if I get fork shudder, lower if the brakes feel spongy. I usually get them dialed in mashing up and otherwise compromising one straddle cable and then replace it with a new one once I know how long I want it.

The best part of cantilevers is their adjustability. The worst part about cantilevers is mechanics and riders without the patience or know how to adjust them properly.

One very important thing left out of cachehiker's reply - it depends on the 'type' of cantilever brake...

If you have a 'low profile' (like modern shimano, Avid etc.) brake then lower is more power/softer feel and higher is less power/firmer feel. How low? Real low. THe lower the better. If you don't have fenders then get the cable so low that the fuzzy molding flash on a new tire will rub on the cable yoke. Then you will see how much power is possible in a rim brake.

If you have a 'high profile' cantilever (like old Mafac or Paul's Neo Retro or SRP) brake then lowering the straddle cable will not give you more power - you want the angle between the straddle cable and the arm of the cantilever to be close to 90 deg. when the brake is engaged, so these ones pretty much need to be high. I don't think these would work well at all with a fork mounted cable hanger.

edit: www.sheldonbrown.com has two excellent articles on cantilever brakes.

Here is the theory

and

here is the practical

IMO, tektro sells a better product.
https://www.tektro.com/_english/01_pr...s&sort=1&fid=5