Both the Sundance SV171 2011 and the Sundance SV205 2008 are modified-V designs, both built in fibreglass, so 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?
On paper these two are close siblings in the size department - Sundance SV171 2011 at 17,1 ft versus Sundance SV205 2008 at 20,0 ft. Weight tells a clearer story for trailering families: the Sundance SV205 2008 tips the scales at 1 850 lbs - 600 lbs less than the Sundance SV171 2011 at 1 250 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.
The power gap is worth calling out. Rated to 200 hp, the Sundance SV205 2008 has a 85-hp advantage over the Sundance SV171 2011's 115-hp ceiling - enough to notice on acceleration and at cruising speed, particularly with a full passenger load. Fuel capacity breaks the other way: the Sundance SV205 2008 carries 45 gallons versus 34 gallons in the Sundance SV171 2011. On a lake day that's negligible, but for coastal cruising or long reservoir runs the extra range matters.
For family outings this is probably the sharpest distinction between the two. The Sundance SV205 2008 is rated for 6 passengers, while the Sundance SV171 2011 caps at 5. If you're regularly pulling extended family or a group of friends onto the water, the extra seats on the Sundance SV205 2008 could be the deciding factor.
Bottom line: Choose the Sundance SV205 2008 if your priority is putting more people on the water - it handles 6 passengers and at 20,0 ft it has the deck room to back that rating up comfortably. The Sundance SV171 2011 is the smarter pick if you want a lighter, easier-to-trailer boat rated for 5 that costs less to run day-to-day.