D/R should impact how much pitch will be imparted to the blades. But it will not be the same as on a plane. It won't be as dramatic as on a plane control surface where 100 might be +/-30 degrees of throw and 50 might be +/- 15 degrees of throw.
By changing to lower D/R settings on the 7200BX you are effectively limiting the maximum roll rate it will attempt with a full stick position. So, in flight, if you do a full stick right ail roll at 100% D/R it will roll at some rate (lets say it's 360 degrees/second, ie. 1 rev per second). At a D/R of 50% that full stick ail roll will now be substantially slower, perhaps 180deg/sec or .5 rev/sec.
On the bench, lower D/R should at some point translate into less pitch thrown. The problem is that it is stationary so the 7200BX will still dial in a great deal of pitch until it actually starts rolling in the direction it is trying to make it go. If you want to see this, try a substantially lower D/R just as a test. Prhaps 40% or even 20%. This should force it's hand and result in less pitch deflection on the bench, despite it being stationary. However, on the bench, the ptich deflection between 100% and 20% D/R will not translate into a typical linearish reduction in pitch deflection. If you were able to measure pitch deflection while in flight, though, it would very much translate into a more or less linear reduction in average pitch deflection.
Another way to see this on the bench is to place the heli on a rotating surface (maybe a lazy susan) use rudder D/R set to 100% put in a stick input and then spin the heli in the direction of rudder input and look at the blade deflection when it comes around to you. Note it. Then set D/R 20 and then spin it again. You should see a substantial difference in blade pitch. You should also see the pitch increase as the rotations slow down.