Absolutely! RPi is cheap but every bit as powerful and complicated as a full PC. I don't see why everyone is saying it will revolutionize programming education for kids. They don't need cheap computers. They need simple computers; a "microworld" in which to play as Seymour Papert would say. That's not the same as an abstracted away or dumbed-down machine. Give them a constrained, simple environment and they'll have fun stretching it in ways you'd never imagine.
Something closer to the Fignition side of the spectrum. (I've personally liked taking my kids back to Papert's Turtle Graphics on such a simple machine: http://bit.ly/figlogo)
Indeed, I think great tooling can really help keep track of stack effects (I'd also say that combinators, rather than dup, swap, drop, ..., make you generally think less about the stack). You should check out the Brief editor as a prototype idea. Just having immediate feedback with step forward/back as you edit makes a huge difference. http://trybrief.com