It's a hard stylometric challenge, just because of its format. The forum posts are probably better for comparison, but what I don't see people doing that I wish they would is comparing what the different Satoshi suspects have written since the forum posts and whitepaper.

Everybody's going to get more similar in terms of topic. Bitcoin actually exists now. There's more to say about it than there was at launch. But does anyone still sound like Satoshi? Or sound more like Satoshi than they did before?

The slight wrench in the works is that it's hard to do this with my personal favorite Satoshi candidate. He stopped writing altogether in 2014, and lost capacity from shortly after the whitepaper came out until he was writing with his eyes by the time he had his head frozen.

He's also the only candidate who seems more likely to me over time, though. The longer things go, the less likely a living person stays tight-lipped.