I've actually gone out of my way to get non-tabbed lenses because I came to RFs from SLRs and can't get rid of my old grip. The 35 Lux ASPH I bought despite the tab because I loved what this particular lens could do (I bought it from a local wedding photog on PN that had gone digital). I have one other tabbed lens, a 24 ASPH but I find the tab on that one not so easy to use as the 35. I think it has to do with the larger diameter on the 35. It would be nice to have tabbed and non-tabbed versions of the lenses but Leica would never do that. Too many people telling them how marvellous the tabs are.
The 24 does not have the smooth focus of the 35 BTW. No grabbing or anything, just not as smooth.