Re: Drag style, material and rating factors?
A long time user of Hardy and Hardy-built CFO spring and pawl reels, I still use some on little rods on small streams. They are not failure proof; I have had cracked leaf springs and, being castings, the frames can crack too. These things are rare but have happened to me. I was an early adapter to mid/large arbor disc drag reels for trout. My experience was and remains that larger trout are brought to net incrementally more quickly (thus released in better condition) by anglers of all skill levels, with a light, smooth, adjustable drag than with an over-run check + palming as in spring and pawl reels. My carry on bag, packed and ready for imminent departure for my annual month-long Western trout adventure, includes; Nautilus FWX, Hardy Ultralite DD and, new and not yet used, Galvan Torque. All these reels feature subtly adjustable drags, aspect ratios featuring reasonably narrow widths and quality, machined from bar-stock construction. #'s 4, 5 & 6 - weight are covered here.
For the salt half or my pseudonym; I have long favored draw-bar, cork, disc-drag reels. Starting with Catino's, I progressed to Abels and Islander. Keep the metal parts oiled and the cork lubed lightly with neatsfoot oil and these reels put the brakes on anything that eats a fly and will last indefinitely. Time marches on and, though I will never head out to the flats without a draw-bar reel in my kit, synthetic, stacked drag systems have earned a place among my outfits. Low maintenance (not that I mind keeping reels clean and lubricated) and lighter in weight, they have a place with today's lighter rods. Hatch, Nautilus NV and my newest winner, Hardy Fortuna X have all proven top notch on both tropical flats and NorthEastern rips.
For the larger line size, bigger game fish reels, large sweep area of drag surface(s) and stout reliability are paramount whereas for lighter line trout rigs, low inertial start-up and fine tunable, linear and consistent drag setting is most relevant. In all fly reels; narrow width for intuitive backing/line uniformity of retrieval and aesthetically pleasing looks, feel and sound are important characteristics.