Previous flying experience whether GA, military or whatever helps a pilot to maintain situational awareness when under pressure. It is the loss of this SA that is the main contributing factor in airline accidents. Some have it better than others.
I believe a good pilot is a good pilot no matter what he is flying. Notice I said good pilot not just a skilled pilot. Having grown up around GA maintenance I saw lots of skilled pilots march into the hangar demanding this and that with little respect or knowledge about what they were saying. I also saw the odd good pilot come in and have a discussion with an engineer and he would listen to the engineer and learn and the aeroplane would be fixed pronto.
What are these bad habits you all seem to talk of? What crap! Resting your foot on the dash is about the only bad habit there is room for in my company, other that it is SOP's which by design remove bad habits from the cockpit.