I have K18's and K24's.

Good – cheap, great modulation, plenty of power.

Bad – Bit of fiddle to bleed. Had to change the master piston on my K24's and that was a RIGHT faff, compared to working on Hopes.

Pad wear isn't as good as my old original minis, but they're not too bad. Getting a few instances of uneven wear though.

The main issue for me, is that I can't seem to get them to mate well with Shimano shifters. I can get them close, but there is too much bulk in the Oro bar clamp to get the shifter as close as I'd like. I have XTRs and XT shifters, both of which will allow me to adjust where the pod sits relative to the bar clamp, but they're not perfect. Irritates me. I may ditch them for saints or something.

I changed becuase I hoped they'd need less maintainence than my hopes. Hasn't really panned out that way.

Also, propel are utterly useless. CRC and UK bikestore carry plenty of spares.