As a developer who moved from a 16gb Intel MBP to an 8gb Air, I see no difference at all. I think a combination of the nature of the SOC and the massively faster retain/release cycle just make it much less of an issue.
That said, I did straight up run out of RAM the other day, but my editor was chewing up something like 32gb of swap. Still no slowdown, though. (I suspect a memory leak, it's very new software)
I'm having no trouble running xCode + iOS simulators at all. In fact I think there's some possibility that the iOS simulator could be lighter weight due to ARM -> ARM rather than ARM -> Intel, but that's pure speculation.
Not currently doing any Android work so I can't comment.
That said, I did straight up run out of RAM the other day, but my editor was chewing up something like 32gb of swap. Still no slowdown, though. (I suspect a memory leak, it's very new software)