dalem, why are they hard to use with 12 ga wire? are you trying to shove the wire into the connector, because you only have to solder it to the top of the male ends don't put the wire inside it.
the Trinity/Corally/Orion connectors work well if they fit in your car, if you want to use these in say a RC10B3 you'd have to cut part of the chassis or solder them onto another battery bar. it is easier to ger the deans connectors to work in any car. i personally use Team Orion connectors on my 1/12th scale.