I am having a spa wired this weekend and would like some advice. I have
a GFI (50 amp double pole) cutoff that is going to go 5 feet from the
spa and then a 50 amp regular breaker to go in the main service. #6
will connect all the wires in beteween.

My electrician suggested that I could also add a fused a/c style
cutoff in line to add protection. Is this a waste of money or will it
provide a layer of protection that the GFI will not? He mentioned that
fuses cut off in any unwanted circumstance....I guess referring to an
arc or short or something where the GFI would not fail (other than
ground fault). Also what about an AFCI breaker in the main service?
WIll this play nicely with a GFI cutoff downstream, or will it
constantly trip? Just wanted to know if this was necessary or overkill.

Anyone done anything similar? This is above and beyond code, it appears.