Other than it being the "least powerful" of the bunch, there's not a whole lot to say.
Although, the midplus wasn't sold in the US. That's probably why there's not much discussion on this frame.
I've got an oversize version and it's a great frame (as all the Prince CTS line was). I get the impression that for some reason, the popularity of the Synergy line was less than the original CTS line.
I liked the marketing of these rackets. It was simple and obvious. Provide a line of rackets that have similar specs with regard to overall weight and balance, string pattern, grips, headsizes, face-on shape and cross-section aerodynamics.....but provide them in different "power" levels easily distinguishable by frame width and color scheme.
Now it seems so convoluted.
I think the problem was there was very little representation of these frames (original and CTS) at the professional level. Well, Capriati (Lighting 90 and Synergy DB 26 pj) and Wilander (Graduate 90) did use them at some point.