Bruckner's symphonies have a unique sound signature, and the biggest problem the winners had was that they did not maintain that throughout the entire symphony (and I think all four had that problem to varying degrees).
I have absolutely no idea what you're talking about

The winners did not maintain a "sound signature"...what?
I must say that the variation in tempi did not bother me very much - I may have a preference, but I feel we need to accept the tempo choices and simply evaluate if those choices were executed effectively. I may differ from others in this regard.
Do you mean tempo variation within movements of single performances or tempo variation between different performances? If the latter, I have no trouble accepting a wide range speeds. My favorites go from the swift Norrington to the slow Davies, including Klemperer who is both swift and slow.
Davies 18:40 17:41 9:16 17:49
Celi 17:39 22:40 8:37 15:14
Klemperer 17:02 14:42 9:23 13:48
Stein 16:34 16:03 8:02 13:36
Dohnányi 15:17 16:57 8:28 14:35
Norrington 15:33 15:34 7:56 12:08
Sawallisch 14:17 17:35 8:26 14:33
So the search for my ideal B6 continues....
You're a hard man to please, Neal

Sarge