I really like the laser and will eventually have one on my P3-AT as well. I've not started carrying it yet as I've not yet run it thru the paces on my range. I have the ammo and just have to make the time. I keep forgetting to add it to the pile when I go up to my range.
I have a belt slide about like the one I think you posted a photo of the other day. I'm pretty sure it will fit that. I use vest carry a lot and definetely have that angle covered in spades. With winter coming on that is how I will carry most commonly and I will have it checked out on the range and ready for that.
I have several guns not yet fired by me. I just don't shoot as much these days as I once did but lately I'm getting back to shooting more.