I've had issues with Hitech's not wanting to always center correctly, they will sometimes be one spline off either left or right after trimming. I've had some with no issue, I've had two that always did it. Others have said the same thing to me.
.06 is more than fast enough, especially if your getting slow as you say. A faster response can actually give you more issues if you're hand eye coordination is beginning to worsen. But you can always slow the servo down with the radio if needed.
Most reliable and best all around servos are JR's in my opinon..but I've used everything and only with Hitech's have I actually had any "issue" with, I've just had failures or have damaged others beyond repair (which was not the servo's fault..)