Most of those 'line tests' are rubbish Sam. Think about it - if your 50lb FINS was labelled 30lb, would it be 30lb that breaks at 167%? - or would it be 50lb?
Tuf XP and FINS are both consistent and reliable. In 80lb, XP is better, but Japanese braids are better again (real Japanese braids, not dodgy Chinese ones with Japanese-sounding names).
The reels you're talking about aren't real big, so if you needed a bit of capacity you would do well to go to one of the premium Japanese lines in PE6 like Varivas 10x10, YGK Ultra Jigman or Ultra Castman, or TD Sensor Hyper PE (and I suspect at heart all of those lines are identical). In most braids PE6 is about 60lb, but in those ones the same diameter will give you about 80lb.
You might also want to consider getting a
6000-size spool for your Surf 4500. That will give you a lot more capacity, with no downside.