As someone who has played and staffed many tournaments with score v2, team based and not, my biggest concern (slider acc aside) is combo:score scaling.
Currently, it is actually possible for someone with 98% and a 500-600 combo on a 2400 combo map to narrowly beat out someone with a 1200 combo and 90% accuracy. The problem with this is that the score difference between the 500-600 combo and 1200 combo isn't enough to justify the consistency involved in getting the higher combo. It turns out that for a good few people, it's much harder to maintain higher combos than accuracy, even if you're heavily trained in the area of skill the map requires for you to get a higher combo.
I can't discount the fact that players can tank accuracy in a tournament, but I see the accuracy percentage as a factor of how much a player has spent their time developing their skill up to their point, while combo is represented by not only skill, but how stable they can remain during play, how familiar they are with the maps, etc.
Now, this actually isn't as much of a problem for maps in the 1000 combo range or below, since a player will have a much easier time obtaining a higher proportion of the combo, and accuracy will still play a role, just not as big of one.
My suggestion to this is to make the combo portion of score v2 linear, and decrease the scaling each time there is a combo break (preferrably after 20-40 combo or so, since when players miss, they can sometimes do it in rapid succession due to a tricky part). Some math would have to be played around with, but the concept would be something like 1x scaling to start, 0.7x after first break, 0.5x after second, etc. Also, have this scaling apply and change depending on the biggest combo, as to not punish early breaks. Ex (assumes above proportions): On a 1000 combo map, I broke 3 times and got combos of 50x, 850x, and 100x. The 850x would have normal weight, the 100x would have 0.7x weight, and the 50x wold have 0.5 weight towards my total combo score weight.
The other issue is more of a show thing, but one of the other complaints I've heard about score v2 is that it's boring to watch. People miss the big numbers of score v1, and it's not as enjoyable to see someone FC a 2k combo map to get a score less than 1 mil. My suggestion here is to just multiply the 1 mill by the max combo of the map and some constant. Ex (here I used a constant of 0.03): https://osu.ppy.sh/b/221777 would have a score of 71,640,000 for a nomod SS. This may seem silly, but I think it would make the audience as well as maybe even the players happier overall.
That's pretty much it, the weights are fine at lower combo lengths, but the combo:score ratio is messed up at higher ones.
Currently, it is actually possible for someone with 98% and a 500-600 combo on a 2400 combo map to narrowly beat out someone with a 1200 combo and 90% accuracy. The problem with this is that the score difference between the 500-600 combo and 1200 combo isn't enough to justify the consistency involved in getting the higher combo. It turns out that for a good few people, it's much harder to maintain higher combos than accuracy, even if you're heavily trained in the area of skill the map requires for you to get a higher combo.
I can't discount the fact that players can tank accuracy in a tournament, but I see the accuracy percentage as a factor of how much a player has spent their time developing their skill up to their point, while combo is represented by not only skill, but how stable they can remain during play, how familiar they are with the maps, etc.
Now, this actually isn't as much of a problem for maps in the 1000 combo range or below, since a player will have a much easier time obtaining a higher proportion of the combo, and accuracy will still play a role, just not as big of one.
My suggestion to this is to make the combo portion of score v2 linear, and decrease the scaling each time there is a combo break (preferrably after 20-40 combo or so, since when players miss, they can sometimes do it in rapid succession due to a tricky part). Some math would have to be played around with, but the concept would be something like 1x scaling to start, 0.7x after first break, 0.5x after second, etc. Also, have this scaling apply and change depending on the biggest combo, as to not punish early breaks. Ex (assumes above proportions): On a 1000 combo map, I broke 3 times and got combos of 50x, 850x, and 100x. The 850x would have normal weight, the 100x would have 0.7x weight, and the 50x wold have 0.5 weight towards my total combo score weight.
The other issue is more of a show thing, but one of the other complaints I've heard about score v2 is that it's boring to watch. People miss the big numbers of score v1, and it's not as enjoyable to see someone FC a 2k combo map to get a score less than 1 mil. My suggestion here is to just multiply the 1 mill by the max combo of the map and some constant. Ex (here I used a constant of 0.03): https://osu.ppy.sh/b/221777 would have a score of 71,640,000 for a nomod SS. This may seem silly, but I think it would make the audience as well as maybe even the players happier overall.
That's pretty much it, the weights are fine at lower combo lengths, but the combo:score ratio is messed up at higher ones.
So Do you prefer ScoreV1 or ScoreV2 ?? 
: 
I had trouble coming up with a reasonable multiplier for it myself, though. Using the old 0.5x multiplier wouldn't make it very useful for scoreV2 tournaments, i think. So i propose something like this: