I'm not sure I would want to get something that would push the limits of the tank at all. I like to have it pretty heavily decorated with plants and driftwood, seems like that would be problematic with large cats. I think a lima is about as big as I would like to go.
SA bumblebees are incredibly tiny. I have one thats at least a year old and he's just over 3" which from what I've read on them that is BIG. Asian Bumblebees get big though, like over a foot big.