L J R:
I returned from a tour in Saudi as a secondee just over a year ago. You pay and conditions are exactly the same as a BAe company man; ie no tax, free accommodation, same leave entitlement etc. The best bit as a secondee is having the RAF "safety net". ie if it all goes wrong you can come back to the RAF instead of being unemployed v quickly.
I enjoyed my 2 & 1/2 years & saved a shed load of money, but it's not everyones cup of tea.