I had posted this info in another build thread of mine, but Ritterview requested this to be a topic of it's own for clarity, so creating this new thread.
During my quest to outfit a new frame, I called Mel @ Tandems East to ask about the Bushnell and da Vinci EBBs (eccentrics).
Here is Mel's EBB lineup with #2 - Bushnell, and #7 - da Vinci:
Mark (tandemgeek on this forum) has the following background information discussing the 3rd gen Bushnell (#2 above) and da Vinci's involvement in its development. http://www.thetandemlink.com/article...eccentric.html
While I do not have both EBBs on hand to compare, mechanically they both seem identical. The most obvious visual differences of the da Vinci are the serrated "teeth" and hole cutout pattern. I took Mel's recommendation and went with the da Vinci which is posted on his website at a very reasonable $120. Other than Tandems East and da Vinci direct, I'm not sure who else is selling this EBB version.
So far, usage of the da Vinci EBB has been very easy and surprising how little effort is needed to tighten the EBB sufficiently to keep it from slipping. Likely the teeth on this model provide more bite/grip in the EBB shell than a smooth surface (ie: Bushnell) would. I' am only guessing because no instructions were provided with the EBB and so a recommended "nm" torque setting is unknown. Perhaps this model would be the same as Bushnell, but I do not have that info. For now I'm using my "sort of firm" setting. After a few rides everything remained just as it was installed and no creaks or other pesky issues that sometimes can occur.
I am still a little concerned with all those drilled out holes letting in gunk and grime around the outside of the EBB shell, but at only 144gm and great grip without much apparent need for cranking on the expansion bolt, it seems like a keeper.
This is a photo of the installed da Vinci EBB: