Possibly off-topic, and perhaps this has been mentioned elsewhere, but I thought it was mildly interesting that Dave Macleod contradicts himself here
, around 30-45 secs in, by stating that Echo Wall (which elsewhere he has argued may "only" be E10) is in fact a bigger deal than Rhapsody (accepted at E11 both by Dave and by subsequent ascentionists).
Re E-grades more generally, to me the only really interesting question is whether the climbing world beyond UK / Ireland will adopt them in any meaningful way?". The rational expectation is surely "no".