I have quite a lot of 120V American equipment that I run at 50Hz via a transformer. As has been mentioned already, items which have simple heating elements or similar (e.g. my 120V soldering irons) couldn't care less about the frequency.
On the radio equipment, I've never had any problems with running at the lower frequency. That said, most of my radio gear is a good many years old, from a time when transformers were often more conservatively rated than today.
When you pass the output from the xfmr through a rectifier to get DC, strictly speaking you would need higher values of reservoir and smoothing capacitors at the lower frequency to keep the ripple down to the same level as at 60Hz. I've seldom found that to be a problem, however, as power supply designs usually build in a fair degree of tolerance in that respect (and tolerances on electrolytic capacitor values are wide anyway).
