Glock 19 MOS vs milling GEN3 Slide

i want an RMR-02 on my G19 G3 (7 years old @ 10K rounds), I either have to have it milled or buy a new slide or buy a NEW G4-MOS. So far, its roughly the same $$. give or take. I may just take the G3 and put a light on in for the bedside weapon. Is there any difference besides the difference in the MOS adapter plate vs. buy/milled slide, other than the tiny bit of height difference, whats the real difference?

Any thoughts or suggestions?
I would like a different perspective,

thank you,