I have to admit that one of the reasons I bought an Icom R-70 was the
difficulty in frequency slewing on my Drake SPR-4 and R-7A
receiver, along with their (relatively) poor frequency stability. I
was quite disappointed in the frequency slewing abilities of the
R-70, with its weird escapades at the 1 MHz band edges, although
it's PLL synthesized tuning was much more precise than the Drake's
PTOs. The R-70's master oscillator (MOX) was not especially stable
compared to current (late 90s) technology, and many times I reached
into the little trapdoor on the top of the case and tweaked the MOX
adjustment pot to zero beat to WWV. I believe that Icom sold a high
accuracy TCXO that would fit the R-70, but I didn't have one.
Nonetheless, I quite enjoyed my R-70. The only reason I sold it was to upgrade to the R-71, with its promise of a better tuning system and memories. The R-70 was much smaller and lighter than the Drakes, and easier to take on DXpeditions. I don't know how accurate it was, but one of my favourite features of the R-70 (and R-71) was the large backlit analog S-meter. It was quite easy to see polar flutter on such a meter. The best log I made with the R-70 was Radio Archangel San Gabriel, LRA-36 in Argentinian Antarctica on 15476 kHz. I found this to be a relatively tough catch from my location in Alberta, and the only way that I could get an intelligible signal was by using ECSS, which was quite easy with the R-70 due to it's 10 Hz synthesizer steps.