The Advantage 20.5 Classic 2009 vs Advantage 21 SR 2009 comparison sits squarely in the category of decisions where specs alone won't tell the whole story — intended use, storage, and long-term ownership costs all factor in.
Size is the most obvious dividing line here. The Advantage 21 SR 2009 measures 21,0 feet overall (2009), giving it roughly 19,0 additional feet of deck space compared to the Advantage 20.5 Classic 2009 at 2,0 feet (2009). Weight tells a clearer story for trailering families: the Advantage 21 SR 2009 tips the scales at 2 975 lbs — 630 lbs less than the Advantage 20.5 Classic 2009 at 2 345 lbs. That difference is meaningful if you're working within a half-ton or three-quarter-ton truck's tow rating, especially once you factor in a motor, gear, and fuel.
For family outings this is probably the sharpest distinction between the two. The Advantage 20.5 Classic 2009 is rated for 6 passengers, while the Advantage 21 SR 2009 caps at 5. If you're regularly pulling extended family or a group of friends onto the water, the extra seats on the Advantage 20.5 Classic 2009 could be the deciding factor.
Bottom line: Choose the Advantage 20.5 Classic 2009 if your priority is putting more people on the water — it handles 6 passengers and at 2,0 ft it has the deck room to back that rating up comfortably. The Advantage 21 SR 2009 is the smarter pick if you want a lighter, easier-to-trailer boat rated for 5 that costs less to run day-to-day.