atblis, I have owned several P9S in 9MM and .45, in both the standard and Target models. I like them a lot and would say they are very accurate pistols in both calibers. That being said, some of my 9MM P9S were not as reliable as the other accurate 9MMs I've owned. I bought a new Walther P88 years ago, reported to be very accurate, but admit I never shot it. The grip was just too big and poorly shaped for me. The P210s are super accurate. I had the 210-2 fixed sight and 210-6 adjustable sighted versions. I've had other 9MMs that were very accurate for me. These would include the SIG X-5, Browning GP Comp, some very accurate 9MM 1911 types, etc, but have found NO 9MM pistol more accurate than the SIG 210. BTW, the P210s, X-5, Browning GPs, 1911 9MMs, etc, even though most are closely/tightly fitted, they are as reliable as any pistols I've owned with any quality ammunition.
I suspect the P9 as in your GB link, is as accurate as the average P9S. Mine appears unfired and I have not shot it to find out.