I also make much more money from going wfp, i did lose ooo i would say around 40 odd in total over aroud 1 and a half years for changing, how ever, iv made more back and they cost more so its quids in really.
Not a lot of running costs, im di only, my resin seems to last for ages, 4 months easy, i do let it run to about 10 on the meter, beleive it or not they just dont streek at the level, i dnt know why. Reg cleans i guess..
But you still cant beat a bit trad, just to keep you on your toes..