Oarhandle speed is controlled, almost absolutely, by the speed of the boat;
the rower having virtually no control over it. The (longitudinal) oarhandle
speed rises from almost zero at the catch to a maximum (2.5 m/s) and then
falls to about 1.5 m/s at the release.
The erg might be improved in this regard by controlling its wheel speed by some sort of stroke damper control program; heavy (opened up) at the catch, decreased to mid stroke and heavier again at the release. Modifying the damper program might make possible the representation of different types and masses of boats.
It is conceivable (but untested) that the change thus imposed on the rower's pull dynamic might more realistically model boat motion on those ergs which are mounted on wheeled tracks. After all if it's the boat's motion that rules the handle speed; perhaps the handle speed can rule the boat's motion.
Too, this improvement would undoubtedly make the rower's erg pull force profile more like that of an oarsman and might reduce the rower's tendency on the erg to increase wheel speed until the handle is under his chin at the release.