To clarify perhaps: when shooting weak hand you're doing it single handed. So as a right handed shooter I shoot left hand only, right hand only, or right hand free style. So there's no need for a ridge on the right side as I'm never going to be shooting with my right hand as support hand. No need to. When shooting support hand only I have no issue getting a solid grip and sinking enough finger on the trigger to have good trigger control.
Does it
help weak hand only? Not in my experience. Does it
hurt shooting weak hand only? No. Does it help rapidly shooting freestyle? Yes.
The Warren sleeve is simple physics. Instead of relying solely on friction (IE stippling) and crushing grip we're putting a significant protrusion to keep the gun from breaking our grip in a two-handed firing position. The flat frame of the Glock has more of an issue in this regard than something that has a rounded protusion to catch the meat of your palm (think 1911 stocks).
I did
not want to like it. It is not sexy. I tried it and could not deny that it works as advertised. It may not fit into the parameters of your mission or provide a measurable advantage due to your level of skill. I don't have one on every gun. But it is not snake oil. At $22.95 shipped you can give it a shot and not be out more than a few lunches at your local joint.
But if it doesn't interfere with week hand shooting would it be best to have the bump on each side? That way it helps on weekhand and strong hand shooting?