That's right. Quad bar has 1mt less than fifth line bar. Also, don't know why. Because this diference, it is very dificulty the conversion.
I found the same problem. My Dyno 18 came with 25mts quad bar, and i was worried about relaunch in marginal winds. That's why i bought a new bar, with fifth line and 31 mts long. It solved my problem giving me a better low end power and also supporting my relaunch in those marginal days.
In time, it is true, Dyno flies very well on 4 lines. I didn't find any diference flying on 5 lines.