The color change in itself isn't detrimental but doing a drain and fill in itself (only removes about 4 qts whereas the total amount is much more than that) won't change the color back to red, which is what you might expect to see.

Many here have alot of opinions on this subject but like your experienced family member, if it were my car I'd do it every 2 years too as I do with my other cars and those cars are very old, high mileage, original trannies, no trannie problems............works for me :)

Those who neglect maintenance can't say that as sooner or later, their stuff breaks and yes, I see that everyday.

W/O changing the ATF, it'll make it out of warranty but if you plan to keep the car for many years, I'd maintain it.

A trans flush will replace ALL the fluid and it'll be red again for a while but it won't stay red in that trans for as long as it does in most other cars. Heat changes the color.

New ATF is better than old dirty, contaminated ATF, no matter what one guy at this board likes to preach whenever he's on an anti-trans fluid change rant. You'll probably see that here too.