Segway could very well be trying to invalidate the Inventist patent. I have no idea. But while their claim is broad, I’d bet it can be circumvented.
As for how aggressive you are with your IP, you are correct, money matters. We recently had our lawyers in to give us patents 101. I believe they said the average to pursue someone infringing is $600K. Obviously there are high-dollar cases to raise that average, but figure your cheapest lawyer bills at $225/hour, it ain’t cheap.
And holy sweet baby jesus, there is no job as dull as patent lawyer. Personally I’d rather work on our assembly line.