Another commander who thinks the Rift mic is rather fantastic for something built-in like this. I've been very impressed with the sound on whole as even the small headphones sound pretty fantastic for what they are. I use my Rift mic for input to both Voice Attack and Discord. At times I'll be chatting in Discord without my Rift on so I switch to the USB headset I used for years before the Rift. It's nothing special, pretty cheap actually - and every time I switch to it people grumble that I sound awful. When I go back to the Rift everyone's happy again and can't believe it's the Rift's mic is sounds so good.
When not playing my Rift hangs from a hanger on the left side of my sim cockpit with the door to the room on the right side, about 15' away. I can walk in the room and in a medium voice, not yelling by any means, and I can speak commands and have VA hear them just fine. I have a few macros that control my Philip Hue lights so I can poke my head in and say "Computer, Lights" (think Star Trek) and boom, the lights fade up perfectly. It's very rare I have to say the command twice. When I'm wearing the headset I never have to repeat commands.
You said you did the initial voice training in Windows, have you done the extended one that takes a good while, like 10-30 minutes? I did that one right after setting up VA so I'm not sure how bad it would have been without it but with it's great for me.
now i can whisper and every command is acted on right away, really don't know what the cause was and I haven't given up fully on the Rift setup just having a rest from fiddling with it and getting on with flying my ships, and reading up on problems others have got fixed in the hope something will fix my problem