What I say? Experience. With a locking axle, the single always made it through where the twin screw with power divider got stuck. The only times the twin screw did good comparatively was when it was equipped with full locking diffs in addition to having a power divider. Weight on tires per given surface area is traction. With a single axle you generally have much higher loading on the tires. Combined with locking axle, it'll often go places no tandem would even consider. Again, I've been there done that.
Not sure what the spec's are on the little truck, but if it's got a long enough frame it would make a good flatbed or stakebed truck for a lumber company, some beer and soda distributors use stakebeds as do contractors. Could also make for a good mechanic's truck. Lot's of uses for a single axle, all depends on how it's set up!
update for the truck... it was on ebay someone paid 6k I told him that I sent the title and he put a dispute on the payment the moment I told him I sent the title, spoke to paypal, they took my side on the dispute and now I almost doubled my money and I just reposted as a no reserve boom! something that I though I was going to end up losing money I just almost double and still more space to make more profit thank you guys!