RJF your pic on the left suggests a slight bias haha. Listen to jerry Cantrell play hollow. Friedman is no slouch. But as hard as I try I can't Eq the marshall out of it and that is what keeps me wondering on the diezel.
Friedman is not my thing, modded Marshalls as far as that goes. If anything I'll take a stock Marshall with a good boost.
Regardless, you have to decide what you would rather have if having both is not an option. Two VERY different amps. One is a 69 Camaro with a blown big block that screams, but is rough around the edges. The Diezel is like an Italian or Swedish super car. Every detail is perfect. Two very different items.