For small scale skirmish, s/d or d/d are far better to be using that staff and I'd swap to them when seeing any small encounter. As for mass zerg busting, fighting from walls, fighting onto walls then you really miss less eruptions and IS than you actually think, those bads following commanders are suckers for punishment and get demolished by these skills. And of course if eruption is missing you're not chucking a LF on top of it but that all comes down to situation.
As for sigils like I said I'm not arguing Fire. I use it on so many classes because it's awesome. But I always start with bloodlust and get the 25stacks, I have a spare staff with this, I also have a spare s/d set with bloodlust sigils for quick pve farming. You can down 5 mobs at a time so fast using s/d and with bloodlust on both weapons you only need to kill 13, it's not really hard or time consuming to regain if you die.