For me it doesn't make sense to change something that is functioning just in case it doesn't, both practically or financially.
If I got say 20 thousand miles before problems then for me that is about 10 years. Given those numbers for 60 thousand miles (needing a further 2 sets of rollers) the cost is probably the same as getting a mod done which just makes it easier the next time, for me that is 30 years and beyond my train of thought. I understand that for higher mileages and different uses the scenario/ratios may change, but for me even at half those miles or life it doesn't make sense and I doubt I will be driving it across India and will have some form of cover as do my other cars if the worst did happen.
If you get 20 thousand miles - great - your lucky. I have known them fail from 4000 kms.....so then the car had to be recovered and then 10 hours labour to rectify the issue in a garage eventually when you can get booked in. And of course they will only replace like for like so another 4000 km's later you might be facing the same scenario again...
Of course you can get cover for anything - but say your halfway on a 2000 mile tour and the rollers fail (btw you don't always get a forewarning of impending failure) then you have to get recovered, then miss the rest of the trip due to the local garage trying to work out what to do with it...
