Only problem with bullets is I would be worried about accidentally shorting them against each other or something else. They dont seem very protected to me. Also depending on how you install them the possibility of accidentally hooking them up backwards. Take a look at the new Losi plugs. They are 5mm bullets with a nice plastic housing around them. I think they are called the EC5 connectors.
But seriously... I havent run accross a problem with deans and have no plans to change.
EDIT: These...
http://www.impaktrc.com/product_info...oducts_id=3272