frw is nice for WSGing, but not really significant
IAS stack is nice since you will have to use fade in tvt unlike in 1v1s, where you always can outstack all kind of slow with BoS
fhr helps you either getting the next cap or gives you some good base life
and the 1 skill of griffon's becomes a bit less important as you dont have to BO on your own in tvts
but there are still the socketing options.
for example a LO rune will help much in tvts where the opponent team involves a trapper as well.
jah/PR can generally increase your life when you feel that you dont need anything else.
i also like ber rune against teams with lots of physical damage and without a trapper in their team. people will argue with AMP etc but it's harder than it seems to keep a faded character amp'd constantly, so the DR actually helps.
FRW and IAS stack are hard to value because they both depend heavily on your opponent team so they might help a lot or might be completely wasted.
soo, if you play on the closed realms i would definitly go for the griffon's route because valk just isn't worth the FGs it costs on my realm and it isnt even that great if you only got one of them. this might differ on other realms, i dont know the prices there.
thats my opinion as far as valk vs griffons is concerned and no matter what, on a trapper griffons is never a bad choice. we got 4 of them lying on our trapper and invested more into jewelry instead, and i bet that our trapper beats 95% of all valk trappers stat wise. and yes, i know that its still kinda subjective. however i can prove it with numbers if needed
well i think the bottom line is that they're both good helms, but there's not really any need to get a valk since it's only better in some situations, and questionable at best.