Your mechanic has given you good advice. The bearings in the idler pulleys will fail before the belt, due to loss and degradation of lubricant.This applies to nearly all engines with a conventional toothed belt drive.

Are you going to drive this car for more than another 92k miles? If not, there is no saving to be made by delaying the change - and a huge potential gain from renewal as long as the job is done properly.

659.

150k on all1.6HDis unless you use it on a race track they will easily do this mileage things move on better materials but there are plenty of people that are still in the dark ages as for the mechanic of course he wants you to change it he has to make a living.