I would personally take "-30% cooldown WHEN IN COVER,+50% Reload WHEN IN COVER" over "trip wire flares" or "field first aid" is most cases.
Further more a vet 1 bonus heavy engineer with no movement penalty as suggested would be able to close in enemy unit go in cover and would clearly over-perform.
Vet abilities and bonuses must be looked at but Royal Engineers vet 1 bonus would be toward the end of the line...
TBH this is one of the rare cases, where tripwire flares are more useful.
REs vet1 looks good until the moment you realize it works only for SMGs, not for brens or piats, where it would be really appealing bonus.
But I'll just stop here. While anvil REs are quite tanky, its not really churchill level, which should be discussed here.