"good" is an adjective. I think I'm going to start a "Stamp Out Adjectives" society, with the motto "numbers not adjectives" ![Smiley :)](https://www.eevblog.com/forum/Smileys/default/smiley.gif)
That's a nice curmudgeonly thought, one to which I'd retort that an SWR of 1.001 is a hundred times better than 1.1. I don't see any reason to believe that a scope with a 1.5 SWR is necessarily going to have a worse (more distorted, less accurate, whatever) trace displayed than one with 1.1. Perhaps it will and perhaps it won't. I decided not to post a long reply here on this so I'll skip the pictures. My 485 is a bit under the weather anyway (horizontal amp slew rate issues at the fastest 3 setting) and I'm done trying to tweak my NanoVNA given that so-so quality of the rest of the kit. The short story is that of the 3 scopes, I can't really say which is the best for a fast edge pulse--they all have their issues. So I might conclude that <1.5 is "good" and that other issues will become more important at this point.
Here's the TDR of a 485 and 2465 input. The TDR has a ~100ps risetime, i.e. better than ~10* faster than the scopes' response.
Vertical sensitivity is 50mρ/div (+100mρ=>60ohms, -100mρ=>40ohms).
Horizontal sensitivity is approx 10cm/div.
Division 1 marked ^ corresponds to the end of the cable.
Thanks for the TDR shots, I wish I had that capability--the NanoVNA 'TDR' isn't quite as nice. However, is that timescale right---about 2.5ns/div? I still have the same questions though--what is the effect on the displayed waveform? If you display a fast edge, do you see corner distortions that correspond?
To try and answer the OP's question I'll just point out again that the VNA (and your TDR) do not show us anything like a 50-ohm resistor in parallel with a 18µF capacitor. That would be drastically different and would have a much, much higher SWR. I can't demonstrate on the NanoVNA at 400Mhz due to parasitics, but I can scale everything down by using a 22nF capacitor, a 50-ohm resistor and a 50-400
kHz sweep. I'd classify an SWR of 8.0 as "not good".