Yes; in fact, if you also manage to get to a Grenth statue at a res shrine in Factions while your region has favor, you can boost your Death Magic by another point.
Seconded... I use the collector's Bleached Skull from Zin Ku Corridor (20% chance of Death +1) and the Bone Spiral Rod from Saint Anjeka's Shrine (20% halves skill recharge for Death). Couple that with the Grenth shrine bonus and you get (sometimes) lvl 20 fiends, lvl 20 horrors, lvl 20 vamp horrors, and lvl 28 flesh golems. (not sure about the minions, haven't tried that yet)
It's funny telling people I can have lvl 20 minions... I get flamed so much for that
There a list anywhere of which shrines are which affiliation? I'd really love to see which areas offer the Grenth bonus. The only one I can think of offhand is the one outside Bai Paasu Reach.