Another attribute of the Blue Racers is that they have a smaller, narrower base with significantly reduced mass.
For many bug ops this can mean that the Blue Racer is more likely to move around on the desk.
Of course any bug can move around and the remedy is some sort of sticky pad underneath.
And the Vibroplex website mentions that the weighting setup on the Blue Racer provides a higher minimum speed. Many Vibroplex bugs, particularly Lightnings,
won't go slower than about 22 wpm, without some sort of modification--a pendulum extender or bigger weight(s).
A good bug for a beginner, which can be easily slowed to about 12 wpm, is the
Vizbug. There's a right-angle version as well as a vertical version and the vertical
can be slowed even more than the other one.
I have a modified Vibroplex Original, a "Verti-plex" which is vertical. Vertical bugs, because of the pendulum arrangement, can be set up for significantly less physical input. Thus they may appeal to ops who are familiar with using paddles.