I have a U5-5R, which I've set up to use (among other things) the analog (NFM) frequencies of the PMR446-band. I've been using it with the stock (136-174/400-520MHz) antenna and a monophone connected using the Kenwood-connector. I'm experiencing some pretty severe static/interference using those bands. I'll add that I'm experiencing said static/interference also when I disconnect the monophone. Short video example here.
I've set squelch to the highest level, which didn't help. Other radios (PMR446-dedicated units) did not experience these issues.
I have been using the radio extensively in the VHF-band, and have not experienced any issues there.