As someone who has been "forced" to compete in an unatural weight class, I do not recommend it. There is literally no point on "making weight" if you're going to be lethargic, weak, and a borderline zombie. I've seen first hand guys that have decent muscle mass that don't destroy themselves trying to make weight, perform extremely well.
Its understandable if you are at a significant height disadvantage to the average, say about 5-8", but if its 1-3", its not a problem. Also it depends on how you fare, I personally do well competing against taller competitors, and have a much harder time with shorter fighters. One reason being, I'm shorter than most of the people I train with, and I'm a forward pressing type fighter than maintaining distance type.
Actually a height advantage is more prevalent in MT than boxing (control 2/3 ranges), so its not too bad. If its a same day weigh in, the most you should cut would be 10lbs. Its uncommon in MT to see a few guys compete in 126, but are around 5'10-5'11. Really the height depends on the region imo. A place where MMA and wrestling is dominant, you'll come across MMA fighters who will be short and stocky, if the place you're competing in is more striking dominant, you'll come across lanky thin guys. So its really a toss up, after finding out where you feel at your best, then research the types of opponent you'll be facing. From my exp in MT, typical strikers are:
110 - < 5'3 (super J123 manlet class)
115 - 5'3
126 - 5'5-5'8
132 - 5'7 - 5'9
140 - 5'8
147 - 5'7 - 5'10
153 - 5'8 - 6'1
160 - 5'9 - 6'3
165 - 5'11+
170 - 6' - 6'4
I don't remember the specific weight class numbers so its more "ish"