Customer service seems to be lacking.
If you take your cover garment off, anything but an IWB will be visible.
That's a moot point.
Shoulder holsters fit a narrow niche. Sometimes it's the only way it will work.
Whether this maker works or not? I don't know, but it sounds marginal at best so far.
I must add, I have never and will never pay $400 for any holster.