Wow - really ~ ? There's an online stopmotion course??!!
I don't think you're going to find any more - not very likely anyway. But there's no reason to avoid the more traditional animation courses - a lot of the really good stopmo animators were trained in traditional 2d or CG animation and just carried the principles over into stopmo.
There's essentially no difference - animation is animation. The only real differences are because we're working with actual flexible sculptures and props that have limitations that don't exist in the more imaginary worlds created through drawing or computer rendering. That's why, whenever people ask how to learn to be a better animator we always recommend books like The Animator's Survival Kit and other traditional cartoon animation sources.
I mean, just look at Justin Rasch as a good example - he learned traditional 2d and CGI before moving into stopmotion. It gives you a solid foundation in the principles - and as with any art form - the way to improve is to work on the principles.
I can understand why you want to bypass the other mediums though - I suppose it does feel counterproductive to spend a lot of time drawing or rendering on a computer if you just want to learn to do stopmo.
Before committing to any course though, try to find reviews by former students (preferably not reviews selected by the institute teaching the course) and see if they're mostly positive or not.
I am enrolled in 2D character animation course and it is of great use. It is good to understand the importance of a 2D character design and animation course, also you can find the best available online courses to do.
Kevin Parry has a stop motion course at Motion Design School.
yeah I was going to do Kevin's course.. I even had a chat with him about his course versus see-learn.com and after telling him I wanted to do more character animation.. he said go for the see-learn.com course.. which I'm now doing.. a few months in now.. they are based in Canada, and this is all stopmotion principles and practice... all good stuff...