Well, I know most of you guys really aren't for the sidearm stuff. I will conccur that us side armers do throw alot of sinking pitches, my Knuckleball sinks and so does my Fastball for the most part, I tend to get alot of break using it and I don't have trouble with lefties really oh and it really makes it easy to throw a shuuto.
Submariners I think generally try to get sinkers because if it goes up and then down it can be pretty nasty.
One thing I noticed about myself in a practice once is. Well I already knew I was ambidextrous but, since a teacher got pissed off at me for using both hands at things in 2nd grade I use left for simple tasks and right for athletics mostly (batting I go left), so one day in practice I threw a few lefty pitches just screwing around and I could throw strikes and had a pretty mean 2 seamer, later on I realized lefty I was going straight over the top whereas right handed I naturally go sidearm.