The spec sheets list the Malibu iRide 2008 as sv23 wake and the Malibu Sportster LX 2005 as modified vee, so check how each hull rides in the conditions you use before you decide.
On paper these two are close siblings in the size department - Malibu iRide 2008 at 21,0 ft versus Malibu Sportster LX 2005 at 20,0 ft. Weight tells a clearer story for trailering families: the Malibu iRide 2008 tips the scales at 2 900 lbs - 650 lbs more than the Malibu Sportster LX 2005 at 2 250 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.
Both boats share a closely matched power ceiling - 400 hp for the Malibu iRide 2008 and 400 hp for the Malibu Sportster LX 2005. Real-world performance will come down more to which motor is actually bolted on, its load at the time, and whether it's a 4-stroke or 2-stroke setup. Both carry nearly identical fuel loads - 41 gal and 38 gal - so range won't be a tiebreaker here.
For family outings this is probably the sharpest distinction between the two. The Malibu iRide 2008 is rated for 10 passengers, while the Malibu Sportster LX 2005 caps at 8. If you're regularly pulling extended family or a group of friends onto the water, the extra seats on the Malibu iRide 2008 could be the deciding factor.
Bottom line: Choose the Malibu iRide 2008 if your priority is putting more people on the water - it handles 10 passengers and at 21,0 ft it has the deck room to back that rating up comfortably. The Malibu Sportster LX 2005 is the smarter pick if you want a lighter, easier-to-trailer boat rated for 8 that costs less to run day-to-day.