As for SD/Northern Shaolin---it is Northern Shaolin. I know this is a hard concept for people to grasp, Sd or not, but it is Northern Shaolin. Are they Northern Shaolin "Forms" as in---what you'll learn from a wushu competition or from a traditional Longfist DVD or whatever? No. But hte techniques are hte same. The movements are the same. The forms are just, well, not "aesthetically trimmed" quite the same or patterned on the same progression of footsteps. SD has its own unique method of teaching that material--some good innovations, some bad ones. You'll only ever know which is which if you try Northern Shaolin and Shaolin-Do.
I've studied Northern Shaolin with a Wushu coach--Longfist--long enough to learn 1 1/2 sets (just under a year), and I've been to a couple of schools claiming to teach Northern Shaolin. Only, SD doesn't teach Northern Shaolin the way Northern Shaolin is taught elsewhere. SD breaks it up, teaches how to throw some heavy duty punches, some sanshou sweeps, etc., and does more conditioning early on. So yeah, it's karatified because it's based on kicking ass. I'm not dissing Northern Shaolin, but ****, no school I went to had a heavy bag in the building and the workouts were paced for geriatrics. SD doesn't do "Tan Tui" or such sets posture for posture, but I guarantee, from experience, that they're just about equivalent. While I do prefer the polish and such of Northern Shaolin to SD, and still I think the Short forms of SD are far superior in application.
You can call me biased, but I'm a pretty hardy critic of both. Honestly, the difference is this: if you want to be able to do the sets you see on kung fu DVD's or in the movies, you can learn those in NS. If you just want to be able to defend yourself using NS techniques, you can do that with SD. Granted, not all SD people can do this. But then, many NS practitioners are out of shape, poorly conditioned, and can't fight worth crap because the principles taught by "Chinese" methods are ****-poor methods for self-defense. SD has some ****-poor theories, too. It's like Ying-Yang, in a way. Most CMA I've seen is incredibly effiminate [Ying-Yang theory or not], and much of SD lacks a dose of reality.
But if you man up, dispense with dancing, and smack yourself across the cheek, you can learn some valuable stuff from either. Personally--and this is the reason I stuck with SD over Northern Shaolin--I think you'd have a better shot at "martial" artistry with SD.