I've owned a fair bit of Heil gear, usually bought used, that has been OK. My main "mike" on my Flex 5000 was Heil and it had an on/off switch that was garbage, actually painful to operate, but was OK enough when I needed it. If I was a regular on a traffic net or something, it wouldn't have lasted a week.
The rest have been better, but not enough for a testimonial.
I've been doing quite well with simple inexpensive, wired ear buds for a long time now and a low cost Yaesu "entry" mike that they give away with rigs. For my minimal SSB use, and CW for that matter, it's plenty good enough. Busted a lot of pileups with no more than that.
I wouldn't advise new hams to spend a lot of money on this stuff, especially if they are DXers. Flex had this incredible built-in equalizer that can make an eight dollar PC mike sound like a million dollars. I've seen the demos.