No scientific data here... I've for the most part, had used vehicles without knowing a lot of their service history. Having heard more than a few stories about a tranny flush that caused or introduced problems, I tended to do the drain and fill a few times over 4 - 6 weeks to dilute the capacity with new fluid. That, being a Mazda that was picky about the fluid spec and quite expensive. I also believe many of those that had problems likley had older or high mileage trannys that were skipped or left too long / neglected as per any services. I do think a new vehicle / owner that follows the maint guidlines from day one is a better bet though. On our cars, we add so few miles that 'affording' these services won't be an issue. I have put less than 800 miles on my VW in the past 5 months being "safer at home" as they say. *I've never bought into the benefit or felt confident of an engine flush.