Plating vs. Bare Brass vs. Lacquer
Instead of giving you my opinion up front I'll instead present my evidence. Following are four videos of Joel Frahm demonstrating Selmer Super Balanced Action tenors at KB Saxophone Services in NYC. He uses the same mouthpiece on every video. I've arranged the videos with the silver tenors first, then a tenor that was seemingly stripped of any lacquer or plating, and finally an SBA with a fair amount of normal lacquer. Headphones will enhance the listening experience. (Also note how Frahm is one awesome sax player.)
The darkest horn of the bunch is pretty clearly the third entry, the apparently unlacquered horn. The brightest horn of the group is arguably the first silver plated horn. Finally, the horn you can most clearly hear the attack and articulation from, to my ears, is the last SBA with the normal laquer. The audible difference between the two silver plated horns is notable with the second horn sounding much darker. Despite the first silver horn's apparent brilliance in tone, it does share the second silver horn's tendency (and the unlacquered horn's, I might add) towards unclear, almost stuffy sounding articulation and attack.
Though this is only a small sample of horns, this is line with my experience. Bare brass, brushed finished and similar unlacquered saxophones tend to have a darker tone when compared to their lacquered or plated counterparts. On the other hand, silver plated horns can sometimes sound dark or bright, but even in the brightest examples there is often an element of stuffiness to them.
Tone of the SBA vs. Mark VI
While all four of those horns have their subtle differences, the contrast between the tone of two different model saxophones can be much more striking. Following are two early Mark VIs, again with the same player and same mouthpiece.
The Mark VIs have clearly brighter tones than all of the SBAs with more brilliant overtones present in the sound. The Mark VI is fairly unique in this way, and the difference can be clearly heard when comparing these two videos with the previous four SBA videos back to back.
Original Lacquer vs. Relacquer
If you listened to Frahm's introductions in the two Mark VI videos you would have noticed the second Mark VI is a relacquer while the first is original lacquer. If there is a difference between the sounds of these two horns than the differences are the subtle of any we discussed so far. This very small sample is also in line with my observations that though a poor relacquering or replating can result in a diminished tone, relacquering (particularly when done well) can result in a tone identical to the original.
While I realize the evidence presented here is not conclusive I hope it is helpful. These realizations have helped me get exactly what I needed when searching for a saxophone.