Well a funny thing, because I just recently managed to try out the DE89 which for some reason I avoided so far. It's a tame razor indeed and the feel is comparable to the Rockwell on 3 or 4, but I still find the Rockwell more comfortable. The Rockwell is more efficient by far though.
So @
Steve Bowles, my experience is just the opposite of yours (assuming the Muhle head being the same as the DE89); the Rockwell turned out to be more efficient as well as more comfortable than the DE89. YMMW.
Slants are a different story, I find my X3 gentler and less efficient than the Rockwell so I guess it's got a niche on it's own