Hi Iluiscl,
You mention the tenor section--that's where I most noticed the woody quality. Yes, it may be the mellow quality of the hammers that contributes to it as you surmise. But as the hammers groove in, that should improve. When you hung the Able hammers, did you include new shanks and flanges? Changing them as well can make a positive difference in the sound too. My Baldwin L Artist Grand is also 6'3", but from 1984. In partially rebuilding it a couple of years ago, I went with Ronsen Wurzen hammers, instead of the Baldwin-specified Renner hammers, and love the sound!
On the Bluthner, if the piano had moderate use and if the strings are older than 25 years, it's possible that they're stretched out by now from repetitive tunings over the decades. New strings might well add to the vibrancy of the sound. If it were to come to that, probably you'd want to order Bluthner strings or strings from their recommended source. For the Baldwin, I skipped the Baldwin SyncroTone strings and instead went with Arledge Bass strings and Mapes International Gold wire for the treble bridge and am most pleased with the results. I believe the instrument sounds better now than when it was new. What this showed me is that in rebuilding, it's not as important to replicate the manufacturer's choices of components as much as attaining the specific sound you want. But with a 90-year old instrument, I understand that perhaps it's best not to get too far afield.
This Bluthner is quite a project for you!