Darting is a per-sled issue. Some do, others don't. Depends on skis, carbides and so on. Let him try it out and if it needs it, get some duallys. My personal favorite are Double-Downs by Snow Studs. There are also Bergstroms' Triple Points. Never used them but are supposedly good but pricey.
Riding this sled is different. Think of it as a dirt bike on a track. Needs a lot of body English to keep it upright in turns. I think he'll enjoy that. It's not a "sit and ride" type sled. Safety wise, it is capable of high speeds 70MPH+ so he has to be a disciplined rider.