On the subject of auxillary tanks it should probably be noted that the Cessna twin series are equipped with just that and have been well presented in the accident stats due to mismanagement of the tanks.
Common threads on there are:
1. Failure to select a tank with fuel in it and making an off field landing with fuel on board;
2. Selecting an auxillary tank with the main tank still full. Excess unused fuel by the engine is then pumped back into the full mains and promptly vented overboard.
Nah, the system used for the Seneca and Seminole is quite good as it is not necessary to fiddle with the fuel selector other than in an engine failure when you want to cross feed or emergency when you want to shut the valve.
FD