In my opinion the 13 pin system does appear to be better with a more secure connection. Prior to buying my 540 I fitted a towbar and 13 pin electrics. When I finally purchased a 540 Murphy’s Law dictated that it had the twin 7 pin system. Adapters are available but it’s a simple enough job to convert - there’s a junction box underneath the van where all the wires are connected. If I’m towing a trailer, which has a 7 pin plug, I use an adapter.