I found that article quite interesting when I ran across it a while ago. I believe there is a lot of truth in there. At the same time, you have to consider the information as it is relative to your situation.

Realistically, how many kilometers do you expect to rack up on that engine after the rebuild? 50,000? 100,000? People have regularly gone further on engines without balance shafts without crankshaft or bearing failure.

So then, how about the vibration? Well, the range that generally gets worse (from what I hear) is the 2-3000RPM range, and possibly beyond that a bit. That's right around where you'll sit at on the highway (with your Evo3 fifth in). I know you're the type of person who enjoys a quiet, vibration-free cabin. It may be worth it for you in that sense.

My personal take is.. if you have balance shafts, with proper maintenance, you can keep them without too much worry unless your engine regularly sees very high RPM. If you don't have balance shafts, don't worry about it (though my lack of balance shafts was partial motivation for a Fluidampr). Unfortunately you seem to be stuck between those scenarios.

Probably not as direct an answer as you were looking for, but maybe some food for thought.