I also noted that most of these places produced medical equipment. Having been on both sides of the game (making medical equipment and working in the medical dodge,) I can see them being upset. I think the tax is a red herring. What they are pissed about is that there will be more scrutiny on the use of tests, particularly those using upscale equipment, in the myriad private labs that buy their output. If the hospitals and big practices can't make an easy buck running or working with private labs, they'll stop. If they stop, the labs quit buying.
Everybody uses basic X-rays; the specialized low energy X-rays, not so much. If insurance companies stop paying higher prices for the special scans, the practices quit using them. The tax is pretty trivial; they'd just pass that on if that was all there was. They are worried that there will be nobody to pass it on to.
My 0.02