Not a techie, so not really qualified to comment on serviceability issues. However at SA average on-wing time for non-Trent core engines was 13 - 14k hours but, since being re-cored, they are getting 21k - 25K plus improved sfcs. Although SA have hour: cycle ratio of 8.25 which helps, JHB ops won't allow de-rated take-offs. I'd be interested to know how these on-wing times compare to typical PW and GE equivalents?