I haven't seen a ton of HS games since 43' was instituted, but the games I have seen haven't changed much since 40'. The strong pitchers are still dominant, the 4 - 5 hitters on most HS teams are somewhat better, but the 4 - 5 weak hitters are still there too. Now as always - the teams that are lucky enough to get a top shelf travel pitcher and a good share of strong travel kids who work smart on their hitting skills are STILL the dominant teams. 40', 43' or 60'6", it doesn't matter - you are toast without quality pitching. The scoring party starts when those 4 - 5 decent HS hitters get a weaker than average battery and string a bunch of hits/walks/stolen bases together.
IMO, the biggest differences are more from kids at ALL positions working harder on their skills than from the 3' added to the pitching distance. The longer distance hardly affects the top pitchers - if anything, it helps their movement pitches. However, the weak pitchers are actually in mortal danger against the best hitters. I absolutely cringe seeing a 50 - 53 mph pitcher throwing fat pitches over the white for experienced hitters.