Well, I can report back that on both 313s and 377s I prefer having the weight of both feet on the pedal at the same time.
When learning to drive on 313s I accidentally verified that there is no grace period if you relax pressure on the DSD pedal and the power handle DSD switch is also up. We went over a poor bit of track and my feet bobbed up for barely a moment. The result was an embarrassed call to the signaller to say I'd had an unsolicited brake application but I knew precisely why, followed by a slightly peeved Competency Development Manager who has to go out and download the unit to verify the UBA was not caused by anything more sinister like a TPWS overspeed. From that I learnt to keep both the handle and pedal down at all times when in motion.
That’s harsh.
I’m always lifting my feet before the vigilance beeps at me out of habit (because the wind noise is so excessive at higher speeds a lot of the time it’s just easier and safer).
Yup. On a 377, if you approach a station from 75mph using step 1 braking, you are almost stopped exactly 60 seconds later. So, if you hit the brakes at just the right point that you don't need to make any adjustment to stop at the right place, it results in the vigilance alarm going off just as you are concentrating on the stop mark. In 377s I routinely blip the pedal as I get close to the station to avoid a distraction at the point of maximum concentration.
It is one of the risks of driving mixed traction. I've come close to blipping the pedal in the same locations in a 313; it's another good reason to always keep the power handle down in addition to the foot pedal.