I have been working in a piano rebuilding shop since high school.  I am
also a musician and have been playing the piano since age six, studying
piano and organ in college.  Personally I have used every hammer choice
that is available.  My conclusion is that the Helmut Abel hammers from
Wally Brooks (Brooks Ltd.) in Old Lyme, CT, are hands down the best
choice tonally and the only hammer that should be used in a quality
instrument.

In defense of a mellow tone, a player piano will get a lot more playing
initially and softer hammers will brighten over time to an acceptable
level.  As far as weight, send the samples from the ends of each section
and if there are changes in rake or pitch those need to be sent also.

Always replace with as close to possible to what was there originally.
This will save the rebuilder/regulator headache while installing them.

Cameron Dean