The only problem with this is the box will calculate the space taken on the hardrive as the same as a video channel even thogh it only takes up a fraction of the space. e.g if you try to manually record 30 hours of radio it'll say there isn't enough space.
Yes it is a long winded way but radio channels only pay a fraction of the cost TV channels do for an EPG slot.
The extended facilities of the EPG which are used for SKY+ and in some cases a standard digibox come at a price that radio stations choose not to pay after all "home taping will kill the record industry" as they said a couple of decades ago
Yes, I take your point about the EPG being the necessary basis for the Sky+ recording system. And as you say, even the highest-profile radio channels are unlikely ever to figure in the EPG as comprehensively as even the lowest-profile TV ones...
One added feature I'd like to see is the extension of the "record what you're watching now" facility to cover radio channels, which I presume could be done without needed full EPG listings.