If you think about it for just a minute you will realize that a plain old Wilson 8 round mag will work for most IDPA stages. Most stages, except for the ones I design, are usually 15 rounds or less. You start with 9 in the gun plus an 8 round reload mag.
A .45 loaded to a 130 pf with a 200 gr SWC is pretty soft shooting. I plan on shooting my .45 at a local match this weekend. I can start with 10 in the gun plus a 9 round reload.
I know I am a Glock fan, but I like to "play" during the winter months with a different gun.