When two boats share the same hull type — in this case both the Allison SS-2000 SuperSport 2012 and the Allison XB-21 ProSport 2013 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 SS-2000 SuperSport 2012 at 20,2 ft versus Allison XB-21 ProSport 2013 at 21,2 ft. At 8 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.
The power gap is worth calling out. Rated to 510 hp, the Allison XB-21 ProSport 2013 has a 120-hp advantage over the Allison SS-2000 SuperSport 2012's 390-hp ceiling — enough to notice on acceleration and at cruising speed, particularly with a full passenger load. Fuel capacity breaks the other way: the Allison XB-21 ProSport 2013 carries 36 gallons versus 24 gallons in the Allison SS-2000 SuperSport 2012. 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 Allison XB-21 ProSport 2013 is rated for 6 passengers, while the Allison SS-2000 SuperSport 2012 caps at 3. If you're regularly pulling extended family or a group of friends onto the water, the extra seats on the Allison XB-21 ProSport 2013 could be the deciding factor.
Bottom line: Choose the Allison XB-21 ProSport 2013 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 SS-2000 SuperSport 2012 is the smarter pick if you want a lighter, easier-to-trailer boat rated for 3 that costs less to run day-to-day.