Hard to answer without knowing more about how you plan to use the RIB. But based on your cool username, I suspect you plan to spearfish from the RIB. In which case, we'd need to know how many spearos will be going out with you. If there is you and a dive buddy then maybe the smaller boat would be nice, with more, I'd suggest the larger boat.
That said, I'm really new to this, so maybe you want to weigh some other opinions a little more heavily.
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