Today, I received a snailmail CD and free chip from this lot. Seems they accept Neteller too, and do seem to pay if you have the good fortune to win.
I recall that the same allegation has been made against Club World and iNetbet, but I pretty much took Club World to the cleaners on their slots a while back with $5 bets, so maybe it is a matter of variance.
RTG casino can alter the way their slots play, but I don't think they can set them below 80% at worst, and more likely 90% would be the minimum. To get a feel for how "tight" they are, check the paytables on some of the well known games, such as 3 card poker, and Jacks or Better video poker, and see how this compares with the Microgaming equivalent, which are "full pay" for these two games. Check paytables with other accredited
RTG casinos and see how the payouts compare. One can perhaps infer what settings they are likely to have chosen for their slots from this information.