[Jon]

I think some are overstating the importance/popularity here - in normal years only the final is of interest to the casual BBC One audience. Obviously this year is slightly different.

I would have agreed in the past. But as has been more or less pointed the semi-finals will probably do better than whatever would go out on a typical Tuesday or Thursday night. 

Assuming they do well this year, I guess they’ll be obliged to try it wherever the contest is next year. 

I think the only potential issue is of exposing the semi-finals to a wider audience, average viewers may feel they’ve had their Eurovision fix and may be produce slightly lower figures for grand final. On the other hand, it might help to build up interest in the Grand Final.