Both the Mariah G21 2009 and the Mariah SX21 Bow Rider 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 - Mariah G21 2009 at 20,0 ft versus Mariah SX21 Bow Rider 2008 at 20,0 ft. Weight tells a clearer story for trailering families: the Mariah G21 2009 tips the scales at 3 900 lbs - 900 lbs more than the Mariah SX21 Bow Rider 2008 at 3 000 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 - 270 hp for the Mariah G21 2009 and 260 hp for the Mariah SX21 Bow Rider 2008. 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 - 44 gal and 44 gal - so range won't be a tiebreaker here.
Both boats are rated for 10 passengers - a good fit for a family of four or five plus guests. Comfort at capacity is another matter; the longer hull typically means more seat options and better weight distribution.
Bottom line: The Mariah G21 2009 and Mariah SX21 Bow Rider 2008 are closely matched on the specs that matter most. Test-ride both on the water you actually use, check current dealer pricing, and factor in long-term service access before you sign.