For my double stacks in strong side IWB I prefer the two belt connections from either an all leather holster or a hybrid style because of the extra stability that connection offers. I also like concealed OWB when the clothing I am wearing allows for it.
I do use a single clip all kydex IWB holster even with something the size of a double stack 45 (30S) and choose it for times when I know moisture from weather or excessive sweating will happen. Since kydex is impervious to moisture and no drying time is needed it does not swell like can happen with a leather holster. It's very handy when I know I'll need to take the holster off and on while I am away from the house because it is so much easier to do than the dual connection holsters are.
Find with the single clip kydex holster it tends to need an occasional adjustment since it "walks" on the belt line a bit with body movement. I have used them all day and just a few hours and overall find that for me the all kydex IWB holsters are not as comfortable as the all leather or hybrid holsters, but they are still a very viable mode of carry and I use them often, especially in the warmer months.
It's good to have options as far as holsters go.