all it takes is a new radio licensee (happens every day) or an old one who got interested in a new part of the spectrum. if they find RFI interfering with the spectrum they are licensed to use, then they'll come hunting for it.I don't think so. AS far as I know it only affects AM radio. If you have a neighbor that listens to talk radio or baseball games he won't like your digital ballast. I haven't seen any that are really shielded yet but it should be possible. My Lumenace and new Lumatek leak RFI. I haven't tested my new Solistek yet. I don't have neighbors but it is still detectable from the road which is not cool.
Also, the cable companies "share" spectrum with the hams. BUT the cable company is supposed to keep it inside the coax. coax is not perfect. when it leaks out and a ham complains...the cable company comes RUNNING to fix the problem. they don't want issues with the FCC (or whatever your country has). Also the power companies also have trucks equipped to sniff out their issues- issues that cause RFI on ham and other frequencies, but their motivation is safety and continuous service generally.
You don't want RFI ever in an urban/suburban environment.
words to the wise.