I have at least four different shoulder holster sets, and two I use fairly regular still. First thing I learned, adjusting and getting any shoulder rig to be comfortable is a time consuming, numerous small adjustment process. I have a "Shooting Systems" which is currently set up for a Makarov, and does see some use, in the four or so months of a year our climate allows enough clothing to not look suspicious. My more often wear is an Uncle Mikes "sidekick" size 0, which carries my Taurus 445 Titanium .44 along with a speed loader under the opposite arm pit.
Both of these are comfortable to wear all day, NOW, but surely were not when first obtained. I'll bet I made some small adjustments to both of these outfits for up to two weeks or maybe even longer, when first starting to wear, but now, in spite of adding more pounds to my belly, they are still comfortable.
The Uncle Mikes was not expensive, about $40 as I remember, with the speed loader pouch, although the Shooting Systems was much more expensive, however can supply additional holsters for different pistols, which can save you well over half of the original cost.
I like shoulder holster carry, during the time of the year when they can be concealed and not draw attention, as you can engage in many activities without discomfort or having to remove. Your mileage may vary. Today, I can not think of any leather shoulder rig I would consider, as even the good ones do not give and will eat you up in tight areas.