With a couple of weeks left before the end of S3, I decided to abandon my Diamond rewards in LAN and go back to NA. I'm done. Never looking back.
I strongly advise against low population servers. My diamond queues were filled with platinum players (sometimes gold). Yes, it's easier to rank in LAN (got to Diamond in no time), but this disparity of ranks in solo queue is jarring. As a main support, and usually first pick, I would go bot lane while the Plat V player in my team got matched against the first pick of the other team, usually a Diamond. I got tired of this.
The state of the LAN server is probably like this (low pop) because of people like me, that decide against transfer. In fact, as a Mexican player, I get better ping in NA, so Mexican players have no advantage transferring over. It's not like Oceania or LAS, servers where people really get a better experience. NA has more players, less queue, and better ping (also the quality of games at highish elo is superb). I honestly don't see LAN server ever getting good.
So I'm back to NA. Decay got me down to Gold 1, but I'm back to Plat 3 in a week. I can carry games now, since the teams are usually evenly matched and the support/vision control that I provide win games. I really regret moving over to LAN, now I shall see if I can get to Diamond in two weeks time.
Edit: Also the queue times are beautiful in NA. 30-40 sec is heaven.