Oh I dunno. R4extra is sort of hilariously amateurish, and quite engaging. I went through the agony of fitting a DAB radio to my car, largely for R4extra.
I do get fed up with BBC not sticking to the roles for each station. When I tune to R3 I expect to hear music, R4 I expect to hear discussion or maybe comedy. Often I hear discussion on R3 and music on R4, and I'm confused. Please stick to your subjects! R4 always has agressive politicking* when I'm driving to work, I don't want that, I want something light hearted, so R4 Extra often fills that need.
* sometimes involving that knob Humphrys, who thinks he's clever. No, he's just an ignorant bad mannered yob.