Speakers with good spinorama charts and with decently low distortion actually sound quite similar as long as they are in their SPL comfort zone.
So, name me one loudspeaker that is not colored, or that doesn't have a sonic signature of its own? We are not talking amplifiers here. With any speaker, anyone can find fault. You come here and say you don't like my speakers. I admit they aren't for everyone. But for what I'm looking for, I couldn't find anything as satisfactory. I certainly would never claim that they are the bees knees. They work for me. I'm the one that's living with them.
FWIW, in a living room it's easy to tell speakers apart. All speakers. None of this "sounds quite similar as long as certain conditions" are met. Back in the day, in a large open acoustic space (usually concert hall), AR would demo their speakers against 'live' sound. I think Wharfedale was doing it too, across the pond. In a large acoustic space, compared with one or two instruments, few could really tell them apart. In a living room? No contest. You know exactly that you are listening to a loudspeaker.
Another example. It's said that Japanese audiophiles (in general) have different acoustic expectations than Americans (or Europeans). There's an outfit in Japan that refurbs old JBL monitor speakers. Kenrick Sound. 4343, 4345, etc. Beautiful work. Most Americans, brought up on box speakers, speakers exhibiting their unique characteristic sound, don't care much for them. Not me. I dig it, and would own a pair if I had even more living room space, and could afford the shipping. But I'm sure they don't have the 'spinorama' you're looking for.