I been using a shoulder rig for 30+ years now, 7 days a week (wearing it now lol). Few things Ive learned...
I carry at about a 45 degree cant, muzzle down. Tilting the grip up makes the draw so much easier especially when seated as I dont have to reach as far to grab it.
Got tired of the leather no stretch belt loop tie downs 20 years ago.
Been replacing them with suspender parts since. Gives me room to move in comfort and I can wear sweats, shorts or whatever else that may not have belt loops. When you reach overhead no one pays no mind when they see the suspenders hooked to your britches but everyone knows what leather tie downs are hooked too.
Also, get the widest shoulder straps you can. (the part where it comes over the shoulders). Its critical to long term comfort.
I would recommend Galcos Miami Classic harness as they have a 2.75 inch wide option. Then you can mix and match and hang any brand of holster, mag yolk/mag pouch that you want. Thats what I did. I went with Swaprigs offering for the holster part to gain the swap ability.
I also have skins for the holster for 1911's, FN509, P320, P365 etc. 5 min to swap. Same rig so fits the same every day no matter what gun you have it skinned for. I tried having a separate rig for different guns/platforms over the years but every time I switched I had to get used to it all over again. Much easier to just swap skins/gun and keep the rest the same. I also added the retention screw as some one else above stated. Its important. Gun has never fallen out since. I replaced the female side with a Texas concho as an ode to my Texas roots.
Interesting tidbit... the threads in conchos are the same threads as holster hardware screws. Who woulda thunk it. Found out by accident one day lol
I added my key reel long ago to my offside, now I dont have to remember them.

I also have a left hand holster and assorted left skins that I can replace the yolk with and carry 2 guns if the need presents itself.
For me I can draw another gun wayyyy faster than a mag swap so thats how I do it. YMMV
My pair of 226's gives me 54 rounds on board ready to rock... if the need presents itself.
Pair of 365's 30 rounds etc.
Ive paired a 226 and a 1911, two 226's and two 1911's in the past and I all could keep thinking all day is why???
Its ungodly heavy and painfull. Hated it everytime.
Same rig with the MK25 (P226) skin on it. 1911 fits in it the same. Oddly enough I dont have any pics with the 1911 in it most likely because I haven't EDC a 1911 in years.
I put this one together for my X Compact. I didnt like how it was full horizontal so I modified that part later to achieve the 45ish degree muzzle down attitude I like but still cant get on board with the thumb break design. Slows me down terribly, It will prolly join the drawer of perfect holsters or get traded/sold off lol
I wound up just getting the 320 skin for the other rig,
So thats been my experiences with shoulder rigs and where I evolved too. Long winded, hope it helps tho.