Since it´s derailed allready, let´s ponder on it a bit, I think the topic is quite interesting...
Michael I checked the thread and it´s a good discussion I think - I actually want to do one "eggplant" Sukhoi in the mid-future (maybe another 34, one of the checking the Kitty hawk kit, or a 30SM, so I follow your works closely - will see...).
My very personal conclusion is that the color:
A: has very strongly changing "blue/violet" component depending on light conditions
B: fades rapidly and loses most of the "A" component in the process, ultimately turning to "simple grey" within time
I think all planes in this color are affected, the more UV they get, the paler/grey the color (which must be of really low quality, since the paling quickly occurs "wildly" irregular on one plane in harder conditions...). The MRP tone IMHO is correct for "brand new few hours out of the paint shop" - older planes already have some fading in them, although unless in "accelerated conditions" as the Syria Su-34, this may happen evenly on the entire plane and do not appear as "weathering".
I really think the RAL 7015 color comparison is taken on a plane that already suffered some paling, so my humble conclusion is that it is a legitimate color choice, depicting a realistic state of this color on a plane of certain age in certain light conditions
My personal approach in painting therefore is to take one particular photo I really like and try to capture the "spirit" of that picture/machine as well as I can, +/- reasonably freely diverting from exact color numbers and adding drops of black/white/blue/yellow to grey tones to get what pleases my eye
31. March, 10:30