After having an X52, X56 and Warthog fail on me, I bit the bullet and bought Virpil...I fly HOTAS too but have the Kb/M set up to shoot as well. Not saying it's impossible but while I can hit 9 out 10 rail shots with mouse, it's only 2 out of 10 with HOTAS, even with curves set. PA's are easier. Maybe my old Logitech is just getting cheesy. I would love to try it with awesomer gear like VKB or Virpil. Maybe someday..
KB/M is impractical for me, being left-handed and never managing to find a flight setup that worked for me, so thousands of hours with a HOTAS may have helped me improve a bit.
I can probably land 8 of 10 Rail shots on average, although, being ancient, some days can be great, another not so

I will agree, without a doubt, that finer control can be gained using a mouse for aiming, so not being picky!