I used Heatsink CNC Cousts for a year on a smooth, theyre pretty good. But now i've swapped to TNN LGM's and oh my god they are insane compared to the Cousts. The CNC backings do make a difference, they make your brake noticeably stiffer if you have the pads set up to the rim perfectly square. For fitting, the Heatsink backings are fine, you just take the pad material out of the current backigns you have got and glue the material into the CNC backings, on the Heatsink website there is a pad fitting guide. Either the Heatsink snowies or yellows (apparently both the same compound just different colours?) are both very good on a smooth, so are the LGM's.