From the BRCA proposal:
It should be noted that EFRA General Rule 2.9 states that for Rule changes that effect more than one Section :- “Unless specified at the (main) AGM all technical Rule changes will be effective 12 months after the rule has been approved.
As the various Electric Classes use different battery voltages, it would require each Section to decide if LiPo cells are suitable.
ME NO LIKE THIS!

... 2010 in worst case now guys...
It could work out well, but chances are much higher now that it won't...