I don't know whether you managed to solve your brake squealing problems Anth73 but I've had luck curing my cantis by tensioning the brake cable and adjusting the centering set screws so I've got the barest gap between my pads and the rim.
I thought I had just been lucky last time I serviced my brakes as I had been noise free for a week or so. Just before leaving work tonight I noticed that I had the slightest bit of brake rub on the rim (which is slightly out of true) . I tightened the centering screw on the side that was rubbing so I had a few more mm's clearance and the noise returned.
Might get my wheel properly trued tomorrow and then hopefully enjoy a quieter ride.
....feeble tecktro cantis
Yep they're the ones I have.
They do seem stronger if the pads don't have to travel far to contact the rim. FWIW I use KoolStop MTB dual compound pads.
They are noise free until they wear down a bit.
I was talking to another CX rider on the weekend who had replaced his cantis with v-brakes. He loved the change.