I think that they should be left where they are. There are two reasons for this:-

1) We are having enough trouble with the small minority on the Island trying to get rid of the TT without giving them another bullet to add to their gun. Leaving it so late would only go to serve more frustration to those who are having their late night (late to them) cup of coco. Yes I know its only another 1/2 hour, but to them it might just go to being the final straw.
2) Just have a thought for the poor Marshalls out there who are already getting it in the ear from their wives for not being at home much during the fortnight. Also just managing to get home befor 10 or 11 at night anyway even before the extra 1/2 hour is put on.

I think its better to keep it the way it is or risk loosing it totally all together.