Have you found that to be the case with all of your pads? When I first tried my Flex, I was using an Sonus SFX-1 cutting pad, and found the combination pretty hard to control. That pad's pretty stiff, and any crease or curve I hit would pull the buffer one way or another. I switched to the orange SwirlBuster pad (conforms to curves just a bit better), and found operation to be much smoother. Another thing I noticed is that you really, really need to make sure the pad is as centered as possible on the Flex. Because of the forced rotation, being off just a little can cause the buffer to want to "walk around". You can get away with being slightly off-center on a PC; the Flex is less forgiving of that.
And one final thing . . . I recall mention in earlier posts that a few Flexes came from the factory with a slightly loose backing plate. You might double-check that center bolt to make sure that's not causing any problems.
Good luck with it. I wasn't sure about the Flex on my first try, either, but the more I use it, the more I like it.
Tort