Interesting. I think the risk you run when doing something like this is that you end up like the Cultural Revolution or the Khmer Rouge. To hold power you need a constantly moving target, and the underlings quickly learn that they just need to point out the marks lest someone point them out. I guess maybe El Salvador is an exception insofar as the tattoos seem to mark the gang members pretty easily, but that's a problem that will solve itself in 5 years as the new gang members adapt. Hard to give up power once it's taken, but on the other hand, the situation there was clearly unsustainable.
The broad lessons of history, from Babylon to Singapore, is that the population will accept nearly anything for stability. A crackdown will be forgiven if it brings stability to the survivors; this is what permits fascism to flourish. Once you have stability, though, you have to make things better. The minute you make things worse you're in serious danger of losing control. Singaporeans view their city as a paradise of order and harmony. Westerners tend to view it as a dystopia. Yet those with an itch for stability are drawn to it - I know a lady who moved there because it made it impossible for her to fall off the wagon. I know a guy who moved there because the leopards would never rip his face off.