I bought a new car with a diesel this year and can find no drawbacks - a 4500 pound sedan getting 45 MPG, beats a Prius all to hell.
I like the idea of a diesel in an airplane, but not $60k diesel engines that can't be overhauled. We are a mess.
The normal person will never run out a 3000 hr engine. Remember, Pt-91 never needs an overhaul, you can just repair and replace parts indefinitely (as long as the engine is supported), so the issue is not really as severe as it may seem.