I have done them both ways. Just recently started fletching with 6 degree right offset. I was told when I bought them that since they are stiffer than most other vanes they may not hold up to offset fletching as well, but haven't had any problems yet. I do think my bh shoot better fletching them offset, but didn't shoot bad fletched straight.
All around I like blazers and will keep using them offset unless vanes are flying off left and right which they haven't yet.