W6,
I don't have a horse in the race as far as FFS, as I'm not really a techie guy - it just doesn't interest me.
The only thing I really like a fishfinder for is depth, temperature, and knowing if sand, rock, or weeds are below me.
The following comments are based solely on my observations from 10 years worth of people staying at the Woodlands (new fisherman every week from May thru October) on Plum Lake.
Plum Lake is a class A Musky and Walleye fishery. I don't think they designate lakes as a class A smallmouth fishery, but there are some absolute tanks in Plum, along with a nice population of nice Crappie. I guess my thoughts on this is that people could spend their time targeting any one of the above species.
Hands-down, the overwhelming majority of people who stay at our cabins (and fish Plum) are bass fisherman, followed by pan fisherman (I'm including Crappie, perch, and bluegill in this bucket) - more people then you'd think chase crappies and Gills for a family fish fry while on a fishing vacation) followed by Walleye.
Musky fishermen are a distant fourth. There's only a small handful of diehard who come up looking for Musky and fish nothing else.
I'm not looking to get into the debate about FFS (as I really have no opinion) to each their own. If you want FFS go for it, if you don't care for FFS then no reason to use it. Based on 10 years of renting cabins, I can speak to the folks who come to the Northwoods and what they're fishing for...
It's kind of funny, customers always ask me where the best spots are for whatever fish they're targeting. I can help them out with panfish, eyes, smallies, and pike, but for musky, I always tell them I have no idea, I don't target skis, and only catch them occasionally by accident.