Last year, I managed to get 3 entries in the week before the dyfi, so its well worth watching the classifieds in the weeks just before the event.
The rough ride and the dyfi are very different types of Enduro, personally I don’t enjoy the Rough ride as its just miles of grassy moorland with very little in the way of technical mountain biking (its just a slog to be honest) where you would be better off with a crossbike rather than a mountainbike (if you do the RR put on some 1.5″ semi slicks to make the climbs a bit less of a chore) whereas the Dyfi is more like a route you would do with your mates, as it has decent descents, and the climbs aren’t that bad and feel like they are worth it for the downs that follow