Shouldn't fail MOT but might show on advisory which isn't good when looking to sell. Dont forget you cant hide from the problems now everything is electronic and some might take the leaving of major faults like AYC as a sign that other areas haven't been looked after (this is in no way a coment dircted at you personally just an observation of Evo buyers).
AYC failure on the X is going to become more and more common and is going to be much worse than on earlier iteration (trust me I've had mine off ans seen how bad they are after 3 years!!!).
Most X failures will be high/low presure plate so fixing kit for less than £100 and maybe 3 hours of spanner work if you're handy. If not, lots of specialists about that can take care of it for you.