Alright, the trackball came in, and I have had a chance to sit down with it.
First off, a 1.5" trackball is SMALL. For comparison, a 3" trackball is about 14 cubic inches, and the 1.5" trackball is only 1.8 cubic inches! So, the 1.5" trackball isn't 50% the size of a full size 3" trackball, but rather only 13%...
Given the super small size, the trackball has an entirely different feel than a traditional 3" trackball. The rollers are decent and the overall construction is certainly industrial quality, but the ball just doesn't have the mass to spin freely if you give it a good whirl. I do not think putting in a heavier ball will change this, as the current ball is quite dense and heavy for its size. Also, due to the small size you really can only have one finger on it comfortably and still control it well, which again feels nothing like an arcade trackball.
So, the bottom line is... it will look cool on a bartop and can fit into a small space, but it really is not going to simulate the feel of an arcade trackball. Since I already have it, I may still use it on my bartop project just to give someone the option to play trackball/mouse games, but I cannot recommend it as a proper replacement for larger trackballs!