When two boats share the same hull type — in this case both the South Bay 529CR Upper Deck 2011 and the South Bay 620CR 2009 are pontoon designs with aluminum construction — the buying decision usually comes down to a handful of practical questions: how many people are you putting on the water, how far do you trailer, and what does your tow vehicle weigh?
The power gap is worth calling out. Rated to 150 hp, the South Bay 529CR Upper Deck 2011 has a 35-hp advantage over the South Bay 620CR 2009's 115-hp ceiling — enough to notice on acceleration and at cruising speed, particularly with a full passenger load. Both carry nearly identical fuel loads — 31 gal and 29 gal — so range won't be a tiebreaker here.
One place where both boats are genuinely identical is tube construction: both run 2 aluminum tubes at 25" diameter. That shared spec means stability and buoyancy characteristics are closely matched — the ride difference you'll feel between them comes primarily from deck length, weight distribution, and motor choice.
Bottom line: The South Bay 529CR Upper Deck 2011 at 29,0 ft is the right call if deck space, comfort, and entertaining are top of your list. The South Bay 620CR 2009 at 2,0 ft wins on trailering ease, likely lower purchase price, and simpler docking — a solid choice for a buyer who wants more boat for less money.