It's just my opinion but I disagree with your second point. It's come to that stage now where there are only a handful of sparrers who are capable of reaching the number 1 spot on the leaderboard, in my opinion. Yes, there needs to be an incentive to spar, like you said, but for the number 1 spot? Nah, something else, perhaps a new currency like 'spar points' which you can redeem for hats at a shop.
I mean think about it, how many GS teams are formed just for the objective of getting past the first round so they can obtain the gift/spar item at GST? I reckon approximately 90% of all the GS teams share this objective in the GST, not to win but to get past the first round and see how far they can go. Therefore, it would be more sensible to incentivise sparring through rewarding players for participating rather then winning imo in a community such as this one.