Nahh, nobody cares about stuff like that. If it's legal in the rules, go nuts. The power weapon type limitation isn't a fluff issue, it's a rules communications issue - your opponent should be able to look at the table and think about what to do without having to constantly ask you questions like, "OK what was this guy's weapon again"? Taking it a step further, yes, if you have multiple models with the same sort of tentacles, those tentacles all need to count as the same thing.