Thanks, folks, for the info. I appreciate it.

As for wear...most of the wear is in the top gear (11T). Less in the 6th and 5th. I typically start in 3rd (mostly flat riding) so the 1st 2 gears have seen no wear and the 3rd and 4th a bit more. I was thinking I might have to use the old spacers for the new cassette. It sounds like there is enough slop in the design that the .2mm difference (5 mm vs 4.8 mm) center-to-center isn't enough of a concern. I might try it both ways just to see for sure.

Re: the HG-30 link on Amazon....any idea if that is better, equal or worse in quality/capability than the HG-50? Is it a replacement?

Re: 12-28. Thanks but I've really enjoyed having the 11T as my top gear.

Thanks again....Cheers...Steph