Here is a Trader/Gardens game against a 40+. I'd actually not seen Baron/Gardens before and wondered if him going into Gardens was a reaction; it was not. He was of the opinion Baron/Gardens was stronger, but I'm skeptical. The game was close, at any rate. added: I'm not sure I want to be buying early Estates in this sort of game. I do think they have some merit in terms of Baron blocking, but as the play shows the relative strength of the Trader deck is that later on it has other things going for it, and thus assisting the rush is possibly deadly.
Interesting game. I, like you, am not sure that buying early Estates is a good idea, especially with $3, though I take your point about Baron blocking.
You skipped a Copper buy at one point -- I assume that was just an oversight?
I might've been tempted to get a second Traders earlier.
But I think that what this game shows is the later-game power of Traders/Gardens:
Turns 15+, =^..^= buys/gains: Island x 4, Copper x 3, Duchy, Silver x 3.
Turns 15+, ackack buys/gains: Lighthouse, Silver x 6, Province (!!), Duchy x 5 (!!)
So, ackack gains 1 more card (well, actually the same net change, with the -1 from exploding his Traders), but his VP compared to =^..^= in the late game are completely one-sided.