One of my tears stuck on today so I'm thinking of replacing both. Anyone used Frentech. They are a good price
Can't speak for their caliper but I've had their guide pin kits for front and back. Not much to report really other than the rear bottom pins were longer than the ones I was intending to take out (by maybe 3mm). As it happened, the existing rear pins were in decent condition so I just cleaned and regreased them and only replaced the rubber boots. Not sure if it would have made a difference but didn't fancy finding out since there was no need.
If you can DIY, it might be worth freeing them off and cleaning first. I destroyed a set of pads really quick on mine, then after I put new pads on and freed off slider, it's been fine ever since.