Great question personally for airsoft they'er just dress up,target shooting indoors pretty good outside however depending on where the sunshines on them(yes we do get it sometimes) from experience not very good at all,I like open sights on all pistols weather RS,airgun or airsoft but thats me.For airsoft blacked out rears and colour upfront is is great,target pistol has to be all blacked out and RS blacked out is all I've ever used but they do look cool as fuck no doubting that ?
Yes the dot is good once its in the window for a nice clear sight picture, but it's much harder to pick up that dot.
Its why you see a lot of yanks running tall irons with a red dot- use the irons to find the dot then use the dot to make the hit.
For airsoft it's kinda meh, i dont think you gain enough advantage from it to offset the slide weight and associated issues. A nice clear set of irons is good enough for those situations where you have enough time that you arent relying on instinct shooting.