Not sure that there is necessarily a consensus, but seems like we all agree that we see very similar good results at 2-2, and 4-1. I believe KB uses 0-something or 0-0? I may be remembering incorrectly on that. Like KB mentioned, some of depends on offensive settings, because the more hard hits, the higher reaction will need to be, particularly on ground balls.
I tested some of these early on, and with my offensive settings, and baserunner speed, i settled in at 2-2 (baserunner speed at 4). Seemed like with anything lower than 2 fielder speed, with my offensive sliders, i began seeing a jump in triples - close to double the normal amount (instead of one triple every 6 games or so, i was seeing one every 3 or 4 games).
I also tested 4-1 early on (and almost every other variation of below-default) and also got good results for Babip. I dont remember what i had the offensive sliders on at that point. I have the data somewhere.
I do know that when i had reaction at default, the infield gobbled up 90% of ground balls. I needed a few more ground balls to get through than the nornal 24%, because back then, line drives were slightly low for me, and on top of that my batting average on line drives stayed a little low as well. So a few more ground balls than normal needed to find their way through to make up for it. That all seems to have improved since then, so i settled in at 2 reaction.