I know a guy who is doing a PPL on a twin but FAA
so realistically on JAA as soon as regulations allow.
What are your reasons for a post basic PPL on a twin? Is it that you have access to one that you wish to fly? It is important especially with a twin that you do enough time on one to keep current and up to speed in the event of the dreaded EF
Many get a twin rating then hardly touch them again. Once you have it then its another rating to maintain so probably better to leave until you have a need for one.
Pace