Another point, not mentioned in the article, is that you can't approach an MRI unit, unless you want to see the magnet rip out of your finger and ballistically destroy stuff on its way to the 1.5+ Tesla superconductive monster bathing in liquid helium.
MR tech here. I once had a minor accident with an angle grinder (well, I've had a few, but this one had side effects) and got several minuscule steel fragments in a finger. I didn't know this had happened, except that once at work (edit: I work on 3T scanners) I could feel them in my finger. They were slightly sore, and very annoying. A few x-rays later I managed to localise them and with the help of a colleague, dug them out with a needle. I never did find them, but we got them out.
I have scanned quite a few people with various sorts of shrapnel in them. Only once was it a problem for the patient (moderate pain) but we don't take the scary ones in - intraocular metallic fragments, one deep in a neck etc.
Ramping takes days (maybe even over a week). The RF is obviously off most the time though, and the gradient magnets are off too - these tend to be the evil bastards. The slew rate messes with your balance and after a few you come to dislike certain sequences - gradient echoes, diffusion and a few other - loud with high slew rates. You feel like your spinning and this causes slight nausea (in me) and 10 minutes or so of vertigo.
Edit for spelling
Well you can have a superconductor with no current running through it. Just charge the electromagnet with current during the scan, then bleed it off gradually when you're done. No need to turn off the superconductivity to power down the magnetism.
And $75k ish of helium - which is getting pricier by the day, and can at times be impossible to source. And the riskiest time in terms of quenches, is during ramping. Our last quench re-occurred just as they finished ramping it. We were down for 3 weeks ish and the cost excluding helium was huge.
/dramatic exaggeration.
Seriously, it can be very problematic, though. See http://www.simplyphysics.com/flying_objects.html