The post by bpwl in that thread:
http://forum.mikrotik.com/t/how-to-set-up-wi-fi-repeater-after-mikrotik-hap-ac-router/164765/1
explains what advantages or disadvantages there can be when using another Mikrotik as repeater/extender or an “easier” device (such as a TP-Link).
Anecdotally, I had once the need to quickly extend the wi-fi to reach a computer in an otherwise never used room, read here how it went:
http://forum.mikrotik.com/t/discussion-mikrotik-configuration-abstraction-complexity/173293/1
The good thing with Mikrotik devices is that (almost) anything is possible with them, but to get them to work even in an extremely simple setup is complex.