The stock PU's sounded amazing. They had their own tonal character and were very versatile within that particular range. They were also succesfully low-humming for a single coil. My idea, however, in installing the Bartolinis were to enhance the tonal range of my Ric. I've been using them for a couple of weeks now.
The neck PU is a split-coil, with the coils organized in a P-Bass fashion. The Bridge PU is a dual-coil humbucker. I also installed the third add-on PU Bartolini has made to replace the mechanical mute system in the bridge. However, I had to carve the bottom a bit to make it fit properly. It was touching the strings otherwise. Its tone is too treble and twangy to use on its own, but I wired it in parallel with the neck PU, as a "treble enhancer". With the neck/mute pair soloed, I can get a nice Ric growl, with enhanced lows. With the bridge PU soloed, the mids are boosted and the thing "barks".
I also tried the mute PU in parallel with the bridge. In that configuration, the neck PU produced a P-bass style fat tone on its own. The bridge/mute pair had a twangy mid tone. However, I felt that I lost the Ric growl in this setup so I preferred the other way. The ideal would be adding a separate volume control for the third PU, which could be done by either drilling a fifth hole on the pickguard or more preferrably changing the "Bass Volume" pot with a stacked one.
The Bartolinis are certainly brighter than the stock PU's and have a more defined sound. The lows are strong without being muddy and the highs are shiny without getting brittle. And yes, they are all "dead" silent PUs. No humming at all. I get the hunch that with a set of roundwounds, I can even dial in a killer slap tone. I had switched to flats to put a rein to the highs and decided that Ric and flatwounds were made for each other. Maybe now it's time to switch back to rounds.
If you are not a Rickenbacker "purist", these units are a nice investment to improve the tonal capabilities of your Ric.