I think Solent that the rules you've quoted apply to PPLs, and that the rules are subtly different for an ATPL. (For a start 100 hrs out of 1500 is small change anyway).
I had a microlight PPL before gaining a JAR PPL(SEP) and wondered why CAA put "microlights" under national-only ratings in the license. It's hard to see why if they put it in there as a rating it doesn't then count for validation.
Personally I think that having to do a microlight GFT is a good thing, there are quite a few differences in handling. In fact I'd probably go one further and say one should take microlight Air-law given that the JAR license syllabus doesn't mention permit-to-fly rules whatsoever.
(I went flying the other day with an ATPL, who has infinitely more flying ability than I ever will, when we did a conventional microlight non-radio overhead join it became apparent that microlight pilots are just a little more familar with signal squares too!).
A friend who is a very (5000hrs+) experienced microlight pilot with a lot of that on taildraggers recently got a PPL(A). The CAA allowed him an automatic tailwheel privilege, rather than making him take the conversion, so common sense is sometimes applied, if not all that often.
G
[This message has been edited by Genghis the Engineer (edited 07 June 2001).]