Hey Folks,
Interesting topic! I have both the gauge type, and the CarbTtune. The amount of Vacuum that the gauges read is irrelevant. It's the difference between each cylinder that needs to be balanced. I sync my Carbs. every spring, but I have OCD! (And I own the Gauge!) Either gauge will do the job as long as you can VERIFY that all four gauges read the same value an a given vacuum.
If you are finding that your Carbs. are out of sync many times during a riding season, then the BUSHINGS in the linkage are worn, and need to be replaced. Keeping in mind that the last model year for the Second Gen. was nine years ago, and the first year of production for the MKI Venture was 39 years ago, it would be safe to say that these little tiny nylon bushings have seen a LOT, even if you have a newer bike! A metal rod pivots on these bushings every time you roll on the throttle, and they are under spring tension even if you are cruising at the same speed for an extended period of time. These parts have a crucial job, and are often overlooked in my opinion. Ownership of the gauge set is not mandatory, Checking the sync yearly IS!
Just sayin',
Earl