Gate of Infinity is awesome. If I read it correctly, it still allows for a vehicle the Primaris is in to move after teleporting, as it is technically one model, there is no risk. I am sure my Vendetta's pilot was getting dizzy, but my opponent was hating the fact that he NEVER knew where that Vendetta would be coming at him from, and at one point he gave up trying to predict as his 18 tanks were decimated. (He took advantage of two detachments to field 18 tanks, and then lucked out on a Big Guns Never Tire match...
Actually you did not read this incorrectly. Gate of Infinity affects a unit, and transports are not part of an independent characters' unit, they merely transport a unit as in the BRB.
This means that a primaris psyker using Gate of Infinity is a dangerous choice, as most useful squads are large (besides veterans), and relying on a run move to get out of a clumped formation is less than reliable.
On the other hand, gating the primaris psyker alone to avoid scatter wouldn't be all too effective either as the other telekenisis powers aren't terribly brutal when the caster won't survive long.
I think that Telepathy is probably the best discipline for the primaris psyker. With a psyker battle squad, psychic shriek is powerful, and besides that, terrify and puppet master are also quite good, and his Mastery of 1 makes him more likely to get these powers, as he can't cast hallucination and invisibility.