Silly question perhaps but how hard is it for those who ride for fun rather than train (or regularly commute and have better base fitness)? And best suited to CX or MTB?
as part of one of the organising club i tail-ended the route last year, the speed differentials are great. and you do have the option of the short route. You can make your mind up on the day, you will also be advised to take the short cut back if you are going very slowly (marshals do want to go home not that i am trying to put anyone off)
If it is dry it is easy, if it is muddy, cotswold dust is soul destroying!!!
This might give some ideas, this is the first half of last years long route, and how fast people are.
https://www.strava.com/segments/11793571?filter=overall