The spec sheets list the Malibu Sunscape 21 LSV 2008 as v25 diamond and the Malibu Sunscape 247 LSV 2011 as modified vee, so check how each hull rides in the conditions you use before you decide.
Size is the most obvious dividing line here. The Malibu Sunscape 247 LSV 2011 measures 24,6 feet overall (2011), giving it roughly 3,6 additional feet of deck space compared to the Malibu Sunscape 21 LSV 2008 at 21,0 feet (2008). Weight tells a clearer story for trailering families: the Malibu Sunscape 247 LSV 2011 tips the scales at 3 900 lbs - 400 lbs less than the Malibu Sunscape 21 LSV 2008 at 3 500 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 555 hp, the Malibu Sunscape 247 LSV 2011 has a 155-hp advantage over the Malibu Sunscape 21 LSV 2008's 400-hp ceiling - enough to notice on acceleration and at cruising speed, particularly with a full passenger load. Fuel capacity breaks the other way: the Malibu Sunscape 247 LSV 2011 carries 87 gallons versus 46 gallons in the Malibu Sunscape 21 LSV 2008. 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 Malibu Sunscape 247 LSV 2011 is rated for 17 passengers, while the Malibu Sunscape 21 LSV 2008 caps at 12. If you're regularly pulling extended family or a group of friends onto the water, the extra seats on the Malibu Sunscape 247 LSV 2011 could be the deciding factor.
Bottom line: Choose the Malibu Sunscape 247 LSV 2011 if your priority is putting more people on the water - it handles 17 passengers and at 24,6 ft it has the deck room to back that rating up comfortably. The Malibu Sunscape 21 LSV 2008 is the smarter pick if you want a lighter, easier-to-trailer boat rated for 12 that costs less to run day-to-day.