Overall, I'm loving the Vauban changes. However, there are a few things that could use some tweaks.
1. Flechette Orb feels like it could be a decent corridor lockdown device if it could hit targets consistently. The damage isn't too terrible (works for most cannon fodder with modest strength mods until higher levels), but the randomness of the shots leaves much to be desired. Allowing it to lock on to a couple of enemies could make it more worthwhile to use (capable of dealing with a few weaker units on its own, but unable to deal with a massive squad marching in without help).
2. Vector pad has very little usage in actual gameplay. Allies aren't that likely to actually try using it for mobility, and there are better ways to move enemies around with Vauban's kit such as Vortex or even Tether Coil (the latter could use either a scaling enemy cap or a larger cap in general). Replacing it with something that can block damage like Stasis Field or even a smaller duration-based Frost globe could help Vauban significantly more than a limited momentum increase.
3. Photon Strike takes too long to fire to be of much use in most squads with teammates that are kill hungry (especially the likes of Mesa, Saryn, etc). The power level is fairly acceptable in most situations in combination with the right ability for the right faction, such as a few seconds under Bastille's armor strip for Grineer. Reducing the activation time by at least one second should alleviate this issue (and if needed, a slight delay before recasting Photon Strike should be acceptable).
4. The cap on the amount of Tesla Nervos drones you can have feels a little unfair for the kind of ability it is. At most I've caught a squad of 4 or possibly 5 enemies in the Nervos trap while the rest of the batallion moves around unscathed. Having at least 6 or 8 would have a fairly significant effect on an enemy squad. This doesn't even need to be all in one cast, the max could be split between 2 fully charged casts.
Beyond those points, Vauban feels pretty good and fun compared to his old self. Hoping to see some more improvements across the board for those that need it.
EDIT: Apparently Flechetre Orb does have some form of lock-on mechanic, however I've noticed a bit of randomness on whether or not it will use said lock-on. Sometimes it sits there shooting at random with nearby enemies, while other times I've seen it try to shoot an enemy standing on a walkway above it