Since I have experience with Danny's services, I'll add a quick note or two.
First he does not decide to just "pick a speaker to tear apart", the speakers he works on are sent in by unhappy clients that respect Danny's work.....just like the owner sending in his 10 year old Wilson speakers.
I own (and love) vintage Reference Series Infinity speakers.....I've owned many pairs, and currently own a pair of Infinity RS Kappa 7s. The crossovers are 40 years old, and use "value" parts. I wanted the crossovers updated with new high quality parts, but using the original schematic.....I sent the schematic to GR-Research to see what they could do.
Danny's team communicated with me all along the way, looked over the schematic, and made some recommendations per my request. They sent me the parts list (and cost) along with some options for various components depending on cost......and why they might decide on the options.
In the end GR-Research built the crossovers mounted on a HDF board, using point to point wiring, that fit well inside the speakers. I've had these speakers since I purchased them new some 35 years ago, and have thousands of hours listening to them......so I know them well of course.
The sound from the Kappas has never been this good. Yes the sonic signature is still there, but the detail, clarity, impact, soundstage, and presence has never been like this. Consider me a happy customer