I have been working as a dog trainer for some time, and my job was to prepare a team of alaskan huskies for Europes longest sleddograce.
I had Voodoo with me, and he did fine in the team (as a swing dog) the first months of training. But when the snow got deeper and the distance got longer, he couldn't cope any longer with the other dogs. He was running with them for about 30km, through snow about 20cm deep en at a pacce of 25km/hour, and that was no problem. But when 1 of those circumstances changed (more snow, longer runs or higher speed), he fell behind. So the last months of training, he was running loose around the sled, jumping on it when he was tired, and making sure the reindeer got of the trail (he loved that part).
For recreational mushing, a team of basenji's can be great fun I'm sure, but for races in deep snow or very bad weather, they aren't the breed you want in front of your sled! Maybe they could finish races like the Iditarod, with nice smooth trails, in a decent time, in a year with realy good weather, but I guess they would have to give up on the first day on the tougher races like the Yukon Quest.
But in opposite of mid and long distance mushing, I would love to see a team of Basenji's in some sprint races. I think they could do very well there and be a suprise to many of the hound-type drivers.
And in a recent study of what is the DNA of the Alaskan Husky's (the dogs that you see most in all the big races), they found Basenji DNA. So the Basenji has been used to create the ultimate sleddog.