OK Paul. I have Internet at the moment, but who knows how long that will last. The over and under pole settings are confusing. One set of numbers sets the absolute hard limit at which the Mesu will simply stop tracking. The other set, as far as I can tell, exists so that if there is an object that is just on the other side of the Meridian, you can get the mount to slew to it without flipping. (It may be useful to do this for a quick observation, or to pick up a couple of quick subs).
If you are concerned about the possibility of a crash, then set the hard limit to a relatively low number. Set the others to be within this. If you go into SkyView (part of Sitech) you get a graphical representation of the limits you set. Pay particular attention to the positive and negative numbers - it was this that was wrong in the original help file. You could follow the pattern I have outlined above, but just reduce the numbers to suit your situation.
If it is any consolation, I 'think' the mount will stop trying to track if it comes up againts a mechanical obstruction. Someone who knows a great deal about these mounts told me this, but I cannot say for certain if it is true or not.
Steve