Using a dial guage, check the runout of the rotors, especially that of
the side which wears pads more heavily.  A rotor with exceptional
runout will cause a "pulsing" feeling at lower speeds, and the
"pulsing" will be directly proportional to vehicle speed.  On a
moderately warped rotor, the pulsing may not be as easily perceived at
motorway speeds as it is in town traffic.

Cheers!

I would think that replacing the calipers would have taken care of
whatever caused the uneven wear (stuck caliper?).  If you are now
getting what you describe as a "buck", I assume that is a one time
"bump" each time the brakes are applied, I would first look for a worn
steering part - most likely candidate would be one or both inner tie rod
bushings.  Other parts could cause a similar effect, but those parts do
go bad relatively often and give such symptoms (as the result of one or
both wheels "flopping" front to back from excessive play in the tie rod
when brakes are applied) as you describe.

There may be other possible causes too, such as strut or strut upper
mount bearing, tension strut bushings, control arms, cradle bushings,
etc.  Suspension and steering parts need to be examined.  Doesn't seem
to me that the "brake imbalance" is related to the problem you now
describe.  Get someone competent and honest to look at this for you -
you don't want a wheel falling off.

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
address with the letter 'x')