Aren't weighted keys just a "feel" thing, though? How important are they?
Bear in mind, though, that I'm specifically interested in learning to use a digital keyboard, not just how to play piano. I'm not really an expert so it's hard for me to tell, but it looks like the ones you suggested are essentially designed to be portable, electronic baby grands, which is fine, but I don't think it's really what I'm looking for.
Perhaps it would be better to use the word "synthesizer", but I'm hesitant to do that since I'm pretty sure that a good one of those would be likely to set me back by umpteen bajillion dollars.