We have only recently turned Gus around. We also have a S&S Meridian. We waited as looooong as possible for safety reasons and made sure he was definitely 8kg before we made the switch. Size wise we definitely could have kept him rear facing for longer (he's only 8.3kg now at 2 years old), but he was getting angry about not knowing where we were going. Think his displeasure at rear facing started when we hired a car with a forward facing seat while on holidays. Biiiig mistake in retrospect, as methinks we might have lasted considerably longer if we hadn't exposed him to the possibility of forward facing.