Agree, however since 2836 movt's that come in rep GMT watches are heavily modified in Asia, they are more prone to failures. This plus when compared to 2893 mov'ts they feel 'crude' and rough to operate, if you ever owned both 2893 and 2863 GMT watches you'd know where I'm coming from. There are many 2863 based 029 and 063 GMT reps that failed in the past, hence the popularity of the real GMT mov't powered reps like ETA-2893 PAM029/063. Ziggy was one of the watchmakers who frowns upon the GMT modified ETA-2836, for example.
ETA-2892 mov't is one of the best and most realiable automatic mov'ts produced by ETA. Its base platform is designed as modular and was also used to build mov'ts with extra complications, like 2892-A2 (with Soprod 9040 PR reserve) module 2893 (GMT function) and 2894 (chronograph).
On the other hand, ETA-2863 is very basic automatic mov't, that's all.
I personaly would steer away from cheaper ones with 2836 mov't in them, and concentrate my efforts to find used pre-owned one with the 2893-A2.