I suspect the fuel burn and tank size make it a short range bird, and one you always want to carry as much fuel as possible. If it has big tanks, the extra fuel will sure eat into the usable.
If you have a 180, why would you want to, in my opinion, downgrade to a Maule?
I realize that on amphibs, some models of 180 become pretty useless on paper. My 180 was on 2425's for decades, had a usable load over 1000#, but those are straight floats.
I want to know if it really is a downgrade for one thing.
I would like to have two planes, an amphib, all modern glass panel, new, and glorious. While I take the 180 out of service, do a major rebuild/upgrade, somewhat modernize the panel, interior, new paint, more power, bush wheels, and not worry about how long it takes me, because I have another plane. A new plane would be a dream come true, shiny and modern.
Or do I do a mild refresh on my 180, slap maybe a pponk in it, and GPS, fix the interior up some, and call it a day...meanwhile buy another 180 that is already amazing, or buy a clunker 180 and rebuild it to be amazing.
The options are endless.
If i had two planes, the amphibious would be flown the most in summer, and then stored in winter, while the other on wheels only goes to Mexico each fall, and is my bop around Mexico plane, fly it back north around April/May, and then only use it occasionally all summer.