i have done RMT a few times over the course of the last 6 years of playing Eve on and off.. Ive had two accounts banned now and each time it was when i purchased PLeX instead of straight up ISK. im not sure if you have better chances with PLeX if you just add the time to your account, or if its just purchasing PLeX in general that screwed me. so at minimum I would like to tell people out there thinking about RMT, go for the ISK instead of trying to make more bang for your buck off the PLeX.
just like with your internet spaceships, if you cant afford to lose your account, dont RMT (or atleast cover your tracks the best you can)