Hi Eddy, great to hear from you too! I feel your pain. For years, I practiced on a 5'3" Bradbury which had hardened hammers too at my parents house. I could never lift the lid on it too for fear that my mom's crystals might shatter.
The dynamic range varied from mp to ff - very difficult to get pp or p sometimes. I could never play the Chopin Nocturnes on it well. I hope you make a choice that you won't regret later. Consistency and predictability is the name of the game here. That's why I think a new set of pristine hammers are very tempting...
So you want to learn regulation? I hope that you do. Ha, I've thought about taking course at the North Bennett School here in Boston. It's an excellent school that teaches how to make, restore, and service all kinds of instruments. I've always had a fascination with color, tone, and timbre. Well, I don't know were you are in your career, but I hope you can retire early to do all these fun things! That's my goal!
I digress, I hope the restoration goes well. Chris restored his Gaveau not too long ago, and it gave birth to whole new piano.