401-425 replacing Gemini 1's and 2's would be a good idea, That is the one I'd personally go for because all of these buses are in good nick for their ages and have shown no signs of slowing down any time soon (from my experiences on them.)
If they were to buy new MMCs for ECB,
I think this would be in 2024, not just because of the repainting process but because the buses can hold for another year longer, and the 841-850 and 937-950 can be replaced in one go together, which would probably be better from a business point of view (Although I'm not a business man and I could be completely wrong on this.)
The priority at the moment should be Airlink with the Edinburgh Airport contract. (For bus orders.) I don't think we should be going on about buses being repainted into Airlink any time soon because ones that are already painted can be used as spares if they order new buses because of contracts etc. At this time we can't predict what is going to happen.
I think they need to start buying new for ECB! Time to stop recycling buses to what are pretty busy and important routes.
The last 23 buses given to ECB (Except 841-850 and 591-594) have been ordered specially for ECB with custom interiors, you have to remember that the buses that they've been given (maybe not 591-594 as such) have been in excellent condition, they're not getting tired buses anymore.
You can argue that 937-950 were very worn when they got them, and that's correct, although the buses have been in East Lothian being thrashed on country routes for all of their lives after being on Airlinks for 12 hours + a day. They're worn out, I think Lothian will replace them all in one go though.
Update: 186 is on its way back from somewhere to Seafield. (Last message posted 22:46 yesterday.)
It tracked at Newbridge. (It's 11:30.)