Ibanez makes some pretty thin/flat/fast necks. I've never owned one, but played a few. The last new electrics I bought were Kramers, if that gives you any idea how up to date I am on this topic. I haven't played a Jackson in over ten years and it was a custom shop strat with a really nice neck/fretboard. I think it would be pretty hard to beat. My current small pile of Kramers, Gibsons, Fenders, etc., seems to have fatter necks than the Jackson set up you are talking about. The Ibanez wide/flat were the thinnest/fastest necks I've played on. Again, I've never owned one, so I can't really recommend it, but do check them out.
