Hi Guys,
Well, as Art has said, this topic certainly stirred up some discussion.
Brian has been just brilliant and has now restored these, undocumented, commands M10P1/M11P1 and E1P0/E1P1 and in the latest version he sent me to test they work just perfectly. There is now no noticeable delay with these commands as can be seen from the picture of the test sample I used.
A big thanks to Artsoft, Brian and the Team who responded so rapidly to restoring these commands which (as others have said) only benefit a very small proportion of the total, worldwide, Mach users. These changes will be incorporated into version R3.043.056 as and when.
Obviously I will no longer be looking at alternatives for my machine control but this has perhaps demonstrated, at least to me, just how fickle we (I) can be.
Tweakie.