Upgrading road and cyclocross bike with a single carbon cross bike
N + 1 is always the answer.  

Seriously though, if you're going to actually use it for cyclocross then I'd advocate buying it as this would be a substantial upgrade.  Lugging 5+ pounds less of a bike over obstacles, up hills, etc, etc over the course of an hour means a ridiculous savings in energy.  

Will this upgrade your cyclocross bike (Kona Jake)?  Yes.

Will this upgrade your road bike?  Doubtful.  The weight difference won't matter as much as the wheels/tires/cockpit/general configuration.

Will it double as a tri-bike?  Doubtful.  Tri-bikes are just too specialized.