Thanks @inertia and @Blockader again. Great points. I currently shoot an SVI 5.4" SightTracker that I use in TacOps and LOVE it. It has, god, somewhere near 40k-50k rounds through it now? It has been fantastic. I am waiting (not patiently) on a Honcho and I will be playing with both the slide mounted with single port comp as well as the frame mounted with the single port comp - MAYBE the 3 port comp if I could somehow come up with a friendly load that would cycle that. The absolute primary priority I have is a holster. One of my earliest and least fond memories of 3Gun is getting DQd on Stage 1 of a 3Gun Nation East Regional when my CZ jumped out of its USPSA style holster. I was frustrated and swore that would never happen and I have been running active retention ever since.
I, like most 3gunners, run my gear way too hard. I prefer the long/terrain style matches (think Hard as Hell or Blueridge etc) so I will need to be finding something with retention and I really just don't know if there is a viable solution yet for frame mounted optic pistols. If someone out there knows better, PLEASE correct me.
As for shotgun mags, I am still trying to figure that out as well. I haven't really thought about the shotgun set up only because I still don't have the Dissident, and based on their wait times, I have no idea when that will be. I have a feeling that getting the belt set up for that will require some creativity.
This is all incredibly fantastic advice that I think any prospective-Open shooter would be glad to see. There is really not THAT much out there when it comes to getting into Open for 3Gun. Thanks guys!!