This system does not need BUDS/ BUDS2. The only time you will need to use BUDS is if you replace the steering angle sensor or replace the steering system. I have been told by people, who once were strangers that I was giving a helping hand to that are now friends for life, of the issues that there have had with their Spyder handling that they have grown to accept, were now gone and it was like riding a new vehicle. How about this, NO more bump steering, No more pulling to the left or right when braking. Due to the accuracy of the system and not doing just go enough, these issues reduced or eliminated. You can have "just good enough" and not have tire wear but still have other issues that you accept as the Spyder.
Yes, of course camber, even though technically non adjustable, can be altered via ride height. Downside though is there is a balance needed between camber and chassis front roll center. If an ideal camber angle of say -1/4 degree were obtained, the suspension arm angles may no longer be conducive to a good front roll center, and / or chassis clearance may not be adequate.
Regarding bump steer, unfortunately, the Spyders simplistic go kart steering design, does not place the inner steering tie rod end in a location that has no bump steer, even in a straight ahead steering angle. Had the designers utilized a wider steering rack, very likely the straight ahead bump steer could have been eliminated. They could have even made a more complex design, with more parts if they utilized a center link on idler arms.
Agree with you regarding a proper alignment will track straight under braking. I have found though, that a setup optimized for minimal rolling resistance with excellent straight line and cornering can get a bit nervous under hard braking. Even though our Spyder has upgraded front suspension, including firmer springs, not just added preload that does not alter spring rate, under hard braking, the front wheels toe out slightly during a hard braking event, and on some occasion, I can feel the front end momentarily squirm side to side. Normal braking is a nonissue. The hard braking, combined with bump steer toeing out both wheels the same amount, causes the squirm.
You mentioned not needing BUDS or BUDS2. That is a curious statement, and impressed you find the need to reset both the steering angle sensor and steering torque sensor after an alignment. Better still, used correctly, the BUDS and BUDS2 is a means to find incoming concerns during an alignment.
Regardless, all the best in your Spyder alignment issues.