A few months/years ago the foundations for the vertical loop had to be reset as because of the shifting landscape, cracks had appeared. Cracks have also been found in the first part of the lay-out, particularly in the downhill helix.
Oblivion = UK!SheiKra approx 1000 miles away. I doubt the UK guests give a damn if there's a longer version in Orlando. They enjoy Oblivion for what it is.
The only issue with keeping Chessington open for two extra hours is that a lot of the time the majority of guests leave the park between 5 and 7. I worked many days over Halloween and every day (with the exception of a 14,000 day) we were running most rides empty. It's not really worth the extra two hours if only a handful of people are going to use it. Young children get tired and there isn't really enough at Chessie to satisfy the older people.Vampire at 10 would be the same as Vampire at 7 and 8.