Imperial Gaurd Allies

Let's face it, the only actual unit we have which is anti-air is probably the Void Raven Bomber which is competing constantly for the heavy support spots which used to be filled with ravagers; however, this can easily be downed by almost any other flier in the game with ease. In comparison, we see the Imperial Guard Vendetta which is fast attack slot, can be put into squadrons!, and have 3 lascannons each with the option of taking heavy bolter sponsons. As a result I was wondering how the rest of the dark city thinks of this allied attachment.

HQ: Primaris Psyker (Psychic Powers!!!)
Troops: 10 Guardsman
Fast Attack: 3 Vendettas each with heavy bolter sponsons

Around 550 points and capable of taking out any air opponents.

I personally wouldnt take the heavy bolter sponsons, but thats just me. Its not needed

Overall I like the idea, but I doubt you need 3. Being able t squadron is nice, but I doubt your need 9 TL lascannons to kill something. You could probably get away with 2 though (remember squadrons act as a single model... so they cant split fire or anything cool)