How Valuable are Signets?

I've been using them on pretty much every character who has useful ones since I prefer stacking base power over utility benefits, but I also resent them since it's also just the game asking you to choose specifically between more abilities or more statistics.

So I'm generally questioning how useful they are now when I'm looking at some other abilities which sound like they'd be really useful to have. My build is completely offensive with heavy critical emphasis; the Precision boosting signet adds around 9% critical chance onto my 64% chance and the Power boosting signet gives around 180 power to my 2100ish base power.

It doesn't sound like a huge difference but I'm also very paranoid about how much it will effect my DPS since my build is exclusively about dealing as much damage as possible.

Signet of Agility is irreplaceable, due to how good extra dodges are. Other than that... eh.