When two boats share the same hull type — in this case both the Allison XB-21 ProSport Bass 2011 and the Allison XB-21 ProSport S.U.B. 2011 are modified vee designs with composite construction — 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 — Allison XB-21 ProSport Bass 2011 at 21,2 ft versus Allison XB-21 ProSport S.U.B. 2011 at 21,2 ft. At 13 lbs and 13 lbs respectively, both sit in a similar weight class — either should pair comfortably with most mid-size SUVs and half-ton trucks, though always confirm your specific tow rating with the motor added.
Both boats share a closely matched power ceiling — 510 hp for the Allison XB-21 ProSport Bass 2011 and 510 hp for the Allison XB-21 ProSport S.U.B. 2011. 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 — 36 gal and 36 gal — so range won't be a tiebreaker here.
For family outings this is probably the sharpest distinction between the two. The Allison XB-21 ProSport Bass 2011 is rated for 6 passengers, while the Allison XB-21 ProSport S.U.B. 2011 caps at 5. If you're regularly pulling extended family or a group of friends onto the water, the extra seats on the Allison XB-21 ProSport Bass 2011 could be the deciding factor.
Bottom line: Choose the Allison XB-21 ProSport Bass 2011 if your priority is putting more people on the water — it handles 6 passengers and at 21,2 ft it has the deck room to back that rating up comfortably. The Allison XB-21 ProSport S.U.B. 2011 is the smarter pick if you want a lighter, easier-to-trailer boat rated for 5 that costs less to run day-to-day.