ARB's are weak by design, plastic parts poor seals and generally unreliable.
KAM I would have said yay but after seeing more than 2 motors running KAM I think I'll stay away from them all together they use their own parts so you can't just refit a landy shaft when it goes tits up.
Detroit I have one great Salisbury one is perfrct Rover ones in recent years have had issues I wouldn;t buy a rover one from anywhere. Salisbury as I said great but you cannot expet the car to drive as it did on road but in a 110 it won't be bad.
ASHCROFT Locker Now they have addressed all the issues with the ARB more engagement metal parts and removed the parts that made them leak air. I would go Detroit or ASH locker
When arbs are used in comps HARD they fail simple, in the last 5 years I have seen most probably 12 fail. Not for me!
Kam Seem to be better but you mess about with the casings and IMO not worth it as you need lots of extras. I do like solonoid engagement tho!
Ash locker seems to be the best in the market but quite pricey
www.ashcrofttransmissions.com