Define reasonable.
I last tried an obs two years ago, but according to my notes it cracked at just over 60 hours of fishing/casting. Some folks might struggle to use a line 60 hours a year. At that rate, $100/year isnβt so bad. Iβm not a guide, and I sure as heck donβt fish as much as a lot of the folks on here (like those you listed), but 60 hours is what I can expect in a non-summer month. In the summer, if Iβm focused on the salt, 60 hours can happen in a week.
6wt rod, double hauling, 6-10β of maxima leader, not cracking the whip or throwing tailing loops, 1-2 false casts, fan casting, shooting 60-90β of line every cast.
My beloved and apparently extinct Airflo 40+ intermediates each stood up to years of this kind of fishing. Call it 500 fishing sessions before Iβd replace them, and even then they were serviceable.
If I were casting the same distance every time I might expect some kind of mechanical fatigue/wear at the rod tip part of the obs. Iβm not.
If I were cracking the whip, throwing tailing loops, or hitting crap with my back cast, I might expect damage on the line. Iβm not. Furthermore, since this longevity issue is limited to RIO linesβespecially the obsβif it were my casting Iβd be breaking other lines. No other line companyβs lines have failed in this way or this fast, either.
If I were stepping on it (Iβm not) or dragging it through cobble/barnacles/oysters/etc, Iβd expect damage. Iβm not. Also, no other line companies lines have failed me in this way or this fast.
I've been told that Airflo uses a different plastic than RIO or SA, but RIO stands alone in the "falls apart fast" group.