I have had great luck with the 209A since it came out. I have recently swapped over to the Rio which is not available in all areas. Hot primers give good cold weather performance, and work well with hard to ignite powders. They generally take less powder to deliver the same velocities as milder primers, which often give cold weather performance problems.
I am done with Fed 209A's, they do not seat flush in Remington STS or Nitro's. I had some problems last week with them not seating, to the point where they caught on the reloader (9000G)and would not index after the shell had been primed. Even the ones that seated, when you run your finger across, you can feel the lip. When loaded in a AA, there is no problem. Win 209's no problem. anyone else have this issue? FYI, I also readjusted the seating etc. made no difference. I even extracted (carefully) the "bad" primers and they went right into the AA's without a problem.
I've loaded nothing but Federal 209As in STS hulls for several years. Yes, I suppose you can feel a very slightly "proud" fit in the shell, but it's never caused any problems with my 9000GN or any of the many guns in which those shells have been used.