Good question, I've wondered too. I absolutely love 4060's with the DPA MMA6000 preamp into the R09, use them all the time for both very loud and quiet field recordings as well as music with both limited and big dynamics, and have never once regretted the purchase. If you are recording quiet things I'd recommend the 4060's over the 4061's for their lower self noise. I also have a single WL183 buried somewhere from my college days 20 years ago but I haven't used it since then, primarily because I only have one so I can't use it for stereo. I've never run it into the R09, only an old Yamaha 4-track back in the day.
The recordings I make now are orders of magnitude better, but the equipment is totally different, what I'm recording is totally different and I am totally different. Not much help I guess, curious to hear others experiences.