Personally I have run both the Evo 4 STI and the Evo 3 STI. The Evo 4 STI has noticeably more torque than the Evo 3 STI and the top speed is marginally faster. This engine is definitely a more aggressive engine as compared to the Evo 3 STI which has a smoother power band throughout.
I have ran about 4-5 gallons on it after break in and did not replace any bearings/ conrod and the engine's performance is still like day 1. My only grouch is that the fuel consumption is slightly more than the Evo 3 STI. The engine tends to cut off at about the 4min30s mark as compared to the Evo 3 which can go up to 5 mins. Perhaps my high end is still on the slightly rich side
I have ran together with Nova and Picco based engines on my track and this engine is definitely competitive in the right hands.