I let KataGo think for ~10k visits from the empty 9x9 board with 7.0 komi.
(0.05 wideRootNoise, recent-ish 28b-network)
Chinese rules:
Stone Scoring:
(click on the images to make them bigger)
The images to the right show the respective principal variations: the first few moves have a lot of visits and can be trusted to be good moves, while the later moves may contain mistakes. However, for Stone Scoring the PV is settled on early and stays stable. Playing it out move by move and letting KataGo think deeper about each move, it still wants to go into the same sequence.
Note that the 4-5 and 4-4 points do not become worse opening moves under stone scoring, instead it is 5-5 that becomes better. In Chinese rules when black opens on tengen, it is quite common for white to end up making two groups. According to KataGo, it is still possible for white to maintain the draw while only making one group, but it seems like the path to doing so is quite narrow. Therefore black gets an “easy” draw by opening on tengen, in the sense that white is more constrained than she would be under Chinese rules (which is reflected in the fact that the principal variation is so stable).
Same stuff for 19x19, with 20k visits:
No significant difference in winrate or score here.
(fun to see that weird opening moves like Q10 only lose ~0.3 points under stone scoring rules - however it should be noted that Q10 only loses ~0.5 points under Chinese rules, so it’s not that unviable there either)