Datasheet -- mentions the 80mbit/sec limitation.
So.. yeah, this router is unlikely to do a great job of amalgamating more than a total of 80mbit/sec of internet-side bandwidth. Dunno if that's 40mbit/sec in and 40mbit/sec out, or what though.
Gotta love vague specifications.
Given that the CPU inside is clocked at only 170MHz, it is unlikely to be a higher performance product. They could have some hardware assistance built-in for NAT and the like to compensate, but this thing is lower spec than many newer home routers.