I've done the quick dash without problems - the gates are manned.
If this is part of a 395 bash, unless the timetable has changed then the most efficient ( as in quickest rather than cheapest ) way of collecting 395 haulages is to do a series of Stratford - Ebbsfleet returns; at Ebbsfleet the cross platform interchange for the return will only be a few minutes whether you are on the high or low level platforms.
From memory a weekly season for this sector is worthwhile for an intense one day bash!
I sampled HS1 today on a 395. Impressed by the class 395! The stations looked strange though with all that concrete and especially as the huge platforms were so empty but I guess they must get busy during peak times