I tend to favor the horizontal Jackass/Miami Vice rig.

The vertical shoulder holsters have always seemed to place the guns grip just a wee bit farther back than I can reach with any speed. I do have one for my 6" barrel guns for hunting purposes.

That's the thing about a shoulder holster though, limited choices. The larger the chest, the farther to reach around. Seems I was blessed with short arms.

Murphy

I have two, Galco Miami Classic for my Baer 1911 and a Galco Classic Lite for my Kahr CT 9, both horizontal carry. I like them mainly for winter carry, seems easier to reach inside of a coat then try and pull it up to draw the pistol. But I have worn them in summer under a button up shirt, unbuttoned, gotta watch for wind gust though : )

Like anything you have to consider the situation.....behind the hip IWB carry sucks while driving or sitting with a coat on if you have to draw. Mush easier with a cross draw or shoulder holster. Walking around, behind the hip will be easier to access and draw less attention...."I am just getting my wallet".

You have to decide what works best for you and the situation. Shoulder holster will help get weight off your waist but can you draw from it effectively? Like Murphy said, reaching around to draw from a shoulder holster can be a issue for some people.

Gunner

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https://www.instagram.com/41gunner/
41 Mags rule, Baers rock!

and most discrete, very good design for handling the weight, and made in a version for autos.
http://www.klnullholsters.com/Holsters.htm

I like the Bianchi X15 when I want to carry a second service size pistol.

I use the Miami rig with a lightweight commander. It is more comfortable than my officers model steel frame.

but they can have issues with concealment depending on the cut of the clothes you have over them. As mentioned, there is also the issue of reaching them for some people. Another issue for a lot of people is the straps not supporting the weight well and creating pain in the shoulder/neck.

I am not a fan of the X15 for automatics because I have had several fall out of them, though they work great for revolvers. Horizontal holsters make some people very concerned because the muzzle is not pointed in the safest direction and you almost have to sweep everyone on your weak side during the draw.

That being said, a well designed shoulder holster that is properly adjusted and used with a well cut covering garment, can be a joy to carry. They offer the advantages of being able to handle large handguns well, are easy to access while sitting, can be accessed with either hand easily and do not create problems if you need to use the restroom.

I have carried everything from lightweight, snub-nosed revolvers, to full size service automatics, and even a 5" 629 Classic, concealed in shoulder holsters with no problems and very comfortably.