My vote would be alignment out of adjustment. I haven't experienced this yet with my V70, but every other car I've ever owned exhibited this trait when it was time for an alignment. I"m not saying it couldn't be rotors also, but only the mechanic will tell for certain: it's shop time.
I think there are a number of threads about this on here, many with people replacing numerous suspension components (struts, tie rods, etc.) trying to make it go away. I think the consensus had been lower control arm bushings. You might have a look at them and check for cracks.
I have never experienced this kind of thing before. but i did suspect that it could be the rotors and yes the car needs an alignment bad.
i ordered the strut mounts and spring seats. and will get it aligned then. my mechanic is going to look at the brakes and check them out.
There are only a few things that will cause your symptoms: calipers, control arm bushings and tire pressure. Tire pressure will cause a pull/drift regardless of accel or decel. Uneven clamping forces (caused by seized or partially seized calipers) from the front calipers will cause one side of the car to slow faster making the car pull to one direction. Also have seen many control arm bushings go bad which allows the wheel to shift during braking and accelerating.