Right, done a little research on this & it appears that for the adverage tat it'll take anywhere from 4-10 laser sessions over a period of about a year to get shot of one, with as you say greens & purples etc being the toughest to get shot of.
Oh and a lot of healing & tlc. The reason I'm curious about this is because I'm seriously considering having one removed. Strange how all of a sudden there are two threads on tats, maybe it's a sign?!?!