I have a gen one Roni for a G17. It's a bit of a kitchie type of thing, I can't shoulder it properly as the LoP is too short. I have a red dot on it, but it needs a riser to properly get behind it. It could also be attributed to the LoP problem?
Having said that, when I take the time to tuck into it, it does make pistol shooting incredibly accurate. 50 meter bulls are effortless.
In my opinion, I don't regret the purchase, but the Roni could have better. I believe the next generation Roni's are better, even if I haven't shot them myself.