Ok, that's fair. I think the design of many moves, and particularly the MC moves, as well as the examples in the book, generally tend to "Pyrrhic victories" falling more often under the domain of 7-9 results, but they can occur, in some cases, on 10+ outcomes or misses, as well. It depends, as you say, on the move and on the fictional situation. (For a simple example, if you were really hoping not to hurt Toyota, and you end up having to "go aggro" to get what you want, then rolling a 10+ might be the worst thing for you - Toyota could choose to 'suck it up' and end up hurt or dead.)
Now, I'll work through this example; it sounds interesting.
Let's say the Savvyhead and Brainer both have Hard=0. I'm guessing a wrench is 2-harm, whereas a Brainer's scalpels are 3-harm (but intimate). Clearly, the Savvyhead wants to take pain wave projector, and is willing to take harm to do so. Same for the Brainer.
Now, I don't know who's the aggressor here, but I'll go with the character who's at a disadvantage first (assuming a wrench is 2-harm).
1. The Savvyhead is Seizing by Force. On a 10+, he might grab the projector and come out ahead in terms of harm (3 points to the Brainer, 2 to him), whereas on a 7-9, he gets the thing but they both take 2- or 3-harm. (Perhaps if the Brainer is cowardly, he might see greater benefit in "dismaying" him, too.) All clear victories, but painful.
On a miss, though, by the old rules things would go against him. Perhaps the MC would offer an opportunity for the Brainer to set off the projector, for instance.
By the new rules, he must choose 1. If he chooses to "take definite hold", he does so, and deals 2-harm to the Brainer, while taking 3-harm. Seems like a reasonable deal - after all, he was prepared to engage in the move in the first place, so he was expecting to get hurt. The very best possible outcome was him taking 2-harm, so taking 3-harm instead doesn't seem (to me) to make a huge difference unless he was, say, at 9:00 harm already.
I don't really see him choosing not to take the thing - after all, if he hands it over, the Brainer could likely kill him with it! Better suck up an additional point of harm.
2. What if it was the Brainer making the move?
The math is similar, except with better harm odds for the Brainer. He's facing 1- or 2-harm (not likely a huge difference, I'd think), and dealing 3- or 4-harm. That's getting into "could kill someone" territory, so that could be interesting if the Savvyhead is already wounded. Killing him would be likely a better deal than grabbing the projector.
On a miss, the Brainer deals 3-harm, suffers 2-harm, and grabs the projector.
Either way, the active party seems almost certain to end up with the device.
Am I doing it right?
Is the idea to make the active party more or less successful by default? To give more agency to being the aggressor in battle situations?
I don't particularly see how the new version is more likely to lead to further fighting or a Pyrrhic outcome. Is it just that we're *always* going to have an exchange of harm, which means that they now have a tough choice facing them if they want to fight further (both being heavily hurt)?
I see simplicity in execution, in that the MC doesn't have to wrack her brains for a miss result, and more predictability. I believe that's what I've been saying all along. However, it could get pretty interesting once death is on the line (if, say, they now go at it a second time). There also seems to be a tremendous advantage given to the active party, whereas under the old rules you risked a painful miss. (As in the first example, getting hit by the pain projector before you get a blow in with your wrench.)
Looking forward to your thoughts (anyone)!