hfd - the NPPL option will ultimately be cheaper.
He currently holds a JAR-FCL PPL with SEP Class Rating and also exercises his privileges on Microlight aircraft.
Upon conversion, he would have a NPPL with both SSEA and Microlight Class Ratings, with expiry dates as for his SEP Class Rating. In order to revalidate these Ratings, once he holds his NPPL, he may take advantage of the new consolidated revalidation requirements:
Holder of a NPPL with 2 or 3 Class Ratings (SSEA/SLMG/Microlight):
(a) Within the period of validity of the rating on any of the classes of aeroplanes held, have flown as pilot:
• at least a total of 12 hours including 8 hours PIC
• at least 12 take-offs and landings
• at least 1 hour training flight with an instructor. If this flight has not been completed all ratings will be endorsed ‘Single seat only’.
(b) Within the 12 months preceding the expiry date of the ratings held have flown, as pilot on any of the class ratings held:
• at least 6 hours flight time.
(c) Within the period of validity of each class rating held, have flown as pilot:
• at least 1 hour PIC on each class held; or
• undertaken at least 1 hour of flying training on each class held with an instructor entitled to give instruction on aeroplanes of those classes.
However, it isn't clear whether his current experience meets all the above conditions. If it does, then it would be reasonable for the NPPL to be issued with SSEA and Microlight Class Ratings valid for 2 years from the date of issue. If not, he can ask any Examiner to revalidate the Class Ratings once he has met all the requirements.