Playing around, Railjack with literally every single speed avionic in existence and the new boost feels about the same as conic nozzle + ion burn and old boost.
The boost itself also runs out far too quickly and takes too long to recharge making most of movement being sluggish and just feels terrible overall
Proposal: either cut the time taken for the boost to recharge by at least half ( shorter strafes and more time moving around) and it would probably feel okay, or increase boost capacity/reduce boost drain by 75% (or at least give us avionics for that.)
And also increase boost multiplier to 1.5x. At the moment boost barely feels like a speed increase until you get to the dash at the end.
Other than that I don't really have much to add, other than RJ missions with objectives being an absolute slog due to aforementioned clunky movement. without those it's barely noticeable because of enemy spawn mechanics. Speaking of spawn mechanics, have the first wave of enemies spawn further away so the squad gets ready before engaging since it does mean teammates occasionally aren't loaded in yet.