Lu,
Any delta 3 effects can be easily worked out when the engineers perform the rigging that then goes into the maintenance manual. Bottom pitch stop on most helos is determined by the auto rpm, in any case.
In other words, no problemo.
Regarding 90 degree pitch horns, the controls are mixed to account for the phase lag, if the horn geometry is changed, all you have to do is re-mix the mechanical controls to make the helo fly right. We have been thru this perhaps 50 times, the way the aircraft handles is NOT affected by the head geometry, as long as the controls are properly mixed. And the Robbie has properly mixed controls.
That 18 degree horse died a long time ago, Lu.