My understanding is the newer Shimano Shifter like the Ultegra 6700s have a longer cable pull so are best suited to a 90mm Mini V like the Tektro RX6. Does anyone have real world experience with this setup?

I’ve used mini-vs with older 105 stis before, no bother at all

That was on road though, rahter than cx, so mud clearance wasn’t a concern

That’s what I’ll be doing.
Were they better than Canti’s?

they were fine, as I imagine a well set-up canti would be but obviously didn’t have to take so much care in the setup of the vs

(haven’t used cantis since about 1949)

I’ve used 6700 shifters with the cheap Tektro mini vees (which are shorter I think) and they were ok. Just had to be careful with out of true wheels.

The other option (which I use now) is a normal v-brake with a Problem Solvers travel adjuster. The travel agent is a bit pricey but normal v-brakes are quite cheap these days.

I can’t remember the numbers now but I went with a cheap Tektro BMX on 5600s, and there was an exact equivalent option for 5700s… I worked back from their TRP range- they’ve got great info on their road mini Vs re arm length, then you can transfer that to the Tektro range. Check out the BMX ones as well as the road/hybrid ones if you’re looking at that end of the market.

They’re good- I get performance from a £13 tektro and stock pads of the sort you’d normally spend a lot of time and money to extract from cantis and posh pads. Fiddlier to change tyres though- needed an in-line barrel because the brakes lack adjusters, and I need to slacken the cable before I can remove the wheel.

Mud and tyre clearance isn’t so simple- on mine, the brakes do stick in more than cantis but they mostly do it in places there’s no clearance anyway because of the frame/fork, so it’s not made a big difference. YMMV. I did get some interference with big (SKS) mudguards and the straddle wire though.

Oh lastly some people complain that it wears out rims faster. It probably does, because they actually provide some friction 😉

I think it’s more the other way around – in order to use 90mm mini-vs you need long pull levers like 6700s whereas the shorter 84mm ones can be use with older Shimano and SRAM and Campag levers without using travel agents.

I’m running TRP 84mm minis (posh version of the Tektros) rather than the 90mm ones as this allows the blocks to sit a bit further away from the rims. Probably get a little less power than the 90mm ones, but easier to adjust and work fine in practice.