Wow a 70s era U87 would indeed be a great mic to have as would the Urei comp.
Honestly your serious recording way predates mine. I should be asking your advise
In the 70s I was fairly serious about sound, but was not into studio recording . I was into and selling high end home consumer audio, things like the Nakamichi 1000 cassette recorder, Macintosh, and Phase Linear amps, and Magneplanaer speakers
It was not until 2003 I got serious about home recording.
That said:: the SOS review of the Camdon is pretty high praise . And the price sounds excellent as well, you can get a pair for what some single channel 500 series pre's go for
I just listened to the video on my laptop earbuds (I'll give a listen later when I have my studio gear fired up. (And I enjoy but am alway cautious about YouTube playback and take it with grain of salt ) But it sounded nice, I think I preferred the non Mojo sound but again could just Youtube and or the laptop
If I were considering 500 I would seriously consider it .
And while I do think in general there has definitely been a steady improvement in the quality vs. price of analog electronics, right along with improvement in digital.
I personally also think in mics, there is still something to be said for , and a little something extra involved with, the upper mid and high end range. But as to whether or not that little extra is worth it to any given individual ? is well up to any given individual .....