As usual with characters that get left behind sometimes, Groove would have been a good character to have a look at in depth, and see what makes him tick. A pacifist who fights to protect people? Who really just wants to explore the world he's in and not have to fight all the time? That, to me, would be a great thing to look into and examine. Sadly, I guess it doesn't make for an exciting kid's show or comic, and certainly wouldn't sell toys. Still, maybe one day IDW will give it a go. I live in hope.
The thing about combiner limbs is that you have to forgive them a lot, and therefore have to have a reason to forgive them. In Groove's case, it's the Tech Specs. Which is a case in point about why I love them so much. Without that, Groove would just be a poor toy with not a lot going for him apart from the fact that he's Defensor's leg. WITH the Tech Spec bio of course, he's a great and interesting character, which makes me like the toy a whole lot more. Tech Specs. Gawd bless 'em.