The Parker Boats 2530 Extended Cabin 2011 is a modified-V design and the Parker Boats 3420 XLD Sport Cabin 2008 is a deep-V 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.
The power gap is worth calling out. Rated to 800 hp, the Parker Boats 3420 XLD Sport Cabin 2008 has a 300-hp advantage over the Parker Boats 2530 Extended Cabin 2011's 500-hp ceiling - enough to notice on acceleration and at cruising speed, particularly with a full passenger load. Fuel capacity breaks the other way: the Parker Boats 3420 XLD Sport Cabin 2008 carries 400 gallons versus 173 gallons in the Parker Boats 2530 Extended Cabin 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 Parker Boats 3420 XLD Sport Cabin 2008 is rated for 10 passengers, while the Parker Boats 2530 Extended Cabin 2011 caps at 7. If you're regularly pulling extended family or a group of friends onto the water, the extra seats on the Parker Boats 3420 XLD Sport Cabin 2008 could be the deciding factor.
Bottom line: Choose the Parker Boats 3420 XLD Sport Cabin 2008 if your priority is putting more people on the water - it handles 10 passengers and at 34,0 ft it has the deck room to back that rating up comfortably. The Parker Boats 2530 Extended Cabin 2011 is the smarter pick if you want a lighter, easier-to-trailer boat rated for 7 that costs less to run day-to-day.