What is the advantage of a 8/8 blade? I honed it and it shaves very nicely. But it sure is big!
There is no advantage to an 8/8 per se.
Some guys like the weight and feel of a heftier blade. All things being equal, an 8/8 is heavier than a 5/8 or 6/8.
Smaller blades tend to be a little more nimble.
All things being equal, larger blades from certain vintage makers tend to be more desirable and cost significantly more than smaller sizes from the same maker
You can shave one side of the face without having to rinse off the lather, they look cool.
I have a hard(er) time with anything under 6/8, but I've found my sweet spot is 6/8-8/8 +/- a hair on both sides.
i am fascinated by the larger blades.... all that i make/made are at least 8/8ths or larger ... including a 12/8ths chopper...
the smallest razor i use is my 11/16ths wolsty pipe razor...
well... thats not quite true i also have/use a KAI/feather type kamisori that i use with feather blades..... wicked sharp but only ~5/8ths.....