I'm not a fan and don't think that the TT is the place for testing prototypes - too much involved in holding a race the economics don't stack up.
However if a race we are having then it at least should be credible - which it isn't. My feeling is that the Mugen bikes have basically taken the challenge out of it by bringing something so out-of-this-world expensive and advanced that many of the teams who had a crack in the past have just decided not to bother. If they want to have a full grid they should make it one of those events where any bike that enters can be bought for a set number of pounds after the event. Lets say 20k for arguments sake.
I've always been a bit ambivalent to the actual race when its on - much like watch the Subarus go past. It's OK for a break in the wait for the racing to start. What I don't agree with is the award of a TT win for it - there is no comparison with an actual TT win.
My guess is that the COC is under some pressure to make sure it happens so various promises and commercial agreements are met. So I reckon it'll be on even if the Senior has to go to 4 laps to fit it in. All the same - good luck to anyone who starts.