The Advantage 29 X-Flight 2009 is a modified-V design and the Advantage 34 Party Cat TRX 2009 is a catamaran design, so you're likely deciding between two noticeably different on-water experiences. Hull type shapes everything from ride quality and fuel burn to dock handling and resale trajectory.
Size is the most obvious dividing line here. The Advantage 34 Party Cat TRX 2009 measures 34,0 feet overall (2009), giving it roughly 5,0 additional feet of deck space compared to the Advantage 29 X-Flight 2009 at 29,0 feet (2009). Weight tells a clearer story for trailering families: the Advantage 34 Party Cat TRX 2009 tips the scales at 8 000 lbs - 3 600 lbs less than the Advantage 29 X-Flight 2009 at 4 400 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 34 Party Cat TRX 2009 is rated for 16 passengers, while the Advantage 29 X-Flight 2009 caps at 12. If you're regularly pulling extended family or a group of friends onto the water, the extra seats on the Advantage 34 Party Cat TRX 2009 could be the deciding factor.
Bottom line: Choose the Advantage 34 Party Cat TRX 2009 if your priority is putting more people on the water - it handles 16 passengers and at 34,0 ft it has the deck room to back that rating up comfortably. The Advantage 29 X-Flight 2009 is the smarter pick if you want a lighter, easier-to-trailer boat rated for 12 that costs less to run day-to-day.