Well, it was me Vs the enitre J world for 6 pages, so I thought I'd give someone else a go for a while - I'm glad others have now waded in!
The reason for the slightly higher J availability, and the reason the J is getting the bulk of the tasking, is actually very simple and may surprise many.
It is nothing to do with the aircraft being newer, or "better" - it is because K servicing schedules are based on flying hours, whereas the J's is based solely on time elapsed. In other words, you can fly the @rse off the J with no maintenence penalty. Why this is so is a mystery, not only to me but to a friend of mine, a highly experienced eng SNCO, who attempted to explain the system to me.
The K fleet has still not really recovered from Saif Sareea, where a whole shedload of maintenance was deferred, setting a precedent we are still stuck with. We now have so many lims and deferred items in F700s that servicing is taking twice as long. And thanks to LEAN we no longer have the engineering manpower to catch up with it.
If you can: A) Get a 'frame in the first place, and B) Get it away from Lyneham, the K is amazingly serviceable for a 40-year old airframe. I can count on the fingers of 1 hand the number of times I've gone u/s away from Lyneham - and I've been around for a while.
16B