The ticket barriers are always operational but the platforms aren’t announced and displayed on screens until a few minutes before departure, similar to what is described as the ‘Euston scrum’
As well as that, staff actively deter you from passing the barrier before the train is announced \ displayed. Even if your ticket has opened a gate and let you through, you will often be escorted back to wait. That has been the normal case ever since the MML platforms have been in their current state on rebuilding of STP.
Best 0 to 60mph acceleration recorded was 44s for both. Never timed a 379 to 100mph but the 387s (similar) get to 100mph in under 2.5min in a similar time to a 360. So virtually no difference
One reason that performance is similar has less to do with how many kW big the motor are and or how heavy or full the unit is, but how much current they can draw. There is a default maximum that applies /almost/ everywhere***; most EMU have traction kit that could exceed this limit, so are capped, and the net effect is to equalise performance since they draw near the capped maximum while acclerating. Often the makers declared maximum acceleration rate is not attainable due to the cap.
*** yes there are some known weak current OLE routes e.g. Kings Lynn, Skipton, to name just two, but it is the very act of limiting the train size or the number of trains that allows that are running to maintain nominal performance