Infusion's effect on your dps depends upon how often you have to heal yourself. I have it on my warden, simply because the points needed to be spent, but wouldn't consider it a priority, to be honest. Its effects on dps are probably going to be negligible, unless you're healing yourself excessively. In that case, your dps is probably going to be less anyway, because you'll be healing rather than doing damage.
Infusion works best in group and raid settings, unless you're tossing spirit of the wolf out to help proc it since all beneficial spells trigger.
