Should have been 9% not 4% Burris/Tasco, and the rest is rounding error.
Almost everyone goes through a process of buying the wrong thing and then buying the right thing later. Some of these guys have been shooting the same Leupold and Nightforce scopes for 6-10+ years (since before I met them); some of them have upgraded to USO/SB; some of them started with USO/SB.
Very few people have shot more than one match with anything "less than" a Leupold M1/M2/M3. Those that try to invariable come better prepared the next match... with a Leupold, NF, USO, or S&B.
Keep in mind that I am talking specifically about field-style "practical" long-range rifle matches. There are different qualities someone wants in a Bench-Rest, F-Class, etc scope vs. this criteria.
If you think about it, it's cheaper to buy the right thing (or one of the right things) from the get-go. Upgrading loses money at every step. If you buy a $300 scope, and then a $600 scope, and then a $1300, and then finally a $2400 scope, even if you get 65% when you resell them used, you've still wasted $2200 x 35% = $770.. which means you could have used that money on training, ammunition, or to get a $3170 scope. Bottom line, it's wasted time and money.
I don't have an answer to your last question. However, I can run down the 2008 SS winners and tell you what people ran, places 1-10: Leu, Leu, Leu, NF, S&B, x, USO, USO, Leu, x. (x= I can't remember.) For the 07 match, places 1-3: Leu, S&B, Leu. For 06, I believe it was S&B, Leu, NF.