Optimal flasher cone size for shallow bows

[the force]

Gents, I'm primarily fishing rainbows in 8-20fow and looking at picking up a flasher. Ive noticed there is a variety, 7 -24 degrees. I'm thinking the widest adjustable range is best, like the birds with a 9-19 degree. Though have seen Garmin strikers are fully adjustable from 16-24 (gt8-if) or 7-16 degrees (gt10if) depending on the ducer. Definitely want the ability to tighten up if I decide to go for perch or lakers. Are there any cons to a wide 24degree cone other than the dead zone from the shallow to deep side if fishing break? Any recommendations or discussion points? Or further adjustable ducers I may not be aware of?

[3300]

any dual beam will work. maybe think more of the other more important features your buying or will be buying. things like digital display or analog. zoom, graph, ir, sensitivity, power, how the transducer is held in the hole. how much repairs will be (very big difference here and you need to know) after warranty. customer service, can it be used year round, ect.