On maps this large, going for tech 3 early becomes viable since you can often defend yourself pretty well and players don't play very aggressively early on. When I reached tier 2 I saw that I wasn't really under any significant threat so I just went for tier 3. Of course, if I was under pressure, it would've sucked majorly.
Props for using artillery, but it's no wonder artillery seems to have such a bad reputation (For being cost inefficient) when people don't micro it. Artillery, left to itself, will consistently chose the most pointless, wellshielded targets. Those T3 mobile artilleries could've easily wiped out most of the opposing frontline forces before the assault had they been told to do so but instead they were left to themselves and attacked a shield.
But all in all, very nice replay, definitly wubworthy.