i feel a 6-7 is fair for my experience also, i may have got lucky with germination rates as mine was slightly better than yours. My first time i don't think i had any fail to sprout, i grew 10 Runtz Muffin, popped 15, and had a variety of others due to their free seeds they give, i had 2 Tropicana Banana, 2 Lemon Tree and 2 Mimosa Evo, i had a high hermie rate first time round, this could of been due to it being a first run and environmental issues, after that run i really enjoyed the Tropicana Banana, its got amazing terps, its got a fruity-ness like no other strain i've come across id definitely recommend anything with Tropicana in the name if you enjoy a fruity strain and the TB with the kush kick from its Banana infusion made it a nice high. Now on my second run in the soil i can say that i definitely had better more consistent environment and have still ended up with herms, luckily this time i've caught them early as i learnt from my past mistakes it broke my heart last time when it went undetected until too late, this could be the nature of feminized seed, genetic or possibly still a rookie error, only more time and experience will tell.
I will definitely check out them banks, ill have to see if they ship to the my country i've tried before with a Californian based company, most US based companies won't ship outside the US/Canada. but it definitely seems the best place to get quality seeds alot of good innovation is happening in the states!