Thanks for the review. Your results are similar to mine. A couple of things I want to mention…
I did manage to make a Cobra 4 pin microphone adapter cable for my 310SDR, following the mic wiring from Panic Attack’s diagram found on his FB page. I can now use my Astatic 575 with the radio and the TX audio is much better. Yes, I lose the mic function buttons, but I can access the front panel of the radio easily. IMO this is the biggest improvement you can make to the radio. Perhaps someone will offer an adapter cable commercially?
When I broke the mic element off the board while trying to remove the mic board (see previous post in the other thread), I contacted BestCB to ask if replacement mics were available. At that time, they were not. Now, BestCB is offering replacement mics for $40. I did replace the element in my stock mic, which cost $1, but good to know you can replace your stock mic. +1 to BestCB.
Simon has posted information about the tuning software for the Midland 8001 Pro being compatible with the 310SDR (and a few other radios). This software has adjustments for modulation, deviation, TX power levels, etc. I have a USB UART cable coming in order to make a cable to plug into the 310SDR and attempt to access some parameters via software. I don’t think there will be much improvement with the software, but I have to screw around with it just to satisfy my own curiosity.