My family owns a 2002 Super Duty 7.3PSD and for farm work its been hands down the best truck we've owned to date. Having said that, I probably drive it maybe once a year at best and when I do I just can't believe how archaic the truck and power is.
My personal truck a 2012 Super Duty 6.7PSD has been extremely reliable to date with 164k miles, and power delivery is far superior to the point there's no comparison.
As for tuned trucks I can't comment from personal experience but around the Houston area there's some really serious tuned 6.7PSD running around that can put some shame on some really fast cars.
The 6.7PSD has quietly received some really large connecting rods and will be getting steel pistons this year, and I look forward to see what kind of abuse these things can handle.
Bottom line I have a lot of respect for both engines. Long live the Power Stroke!