Well, I brought down the poplar yesterday, and it went great. I ended up cutting the stump a higher than normal, since the bottom of the tree was a little crooked and I wanted the block face cut to be above that.
I made the face cut, and the block popped right out with one hit from the axe (gotta love poplar). My only flaw was leaving the hinge too thick -- after tapping in all of my wedges, I had to bore back in and remove a little more hinge before the tree went over. So that cost me a $5 wedge and sprayed some orange chips, but no big deal.
Once the back cut was right, the tree went over smooth as silk and very slow, and landed right where I wanted. There was a lot of groaning from the hinge fibers that I haven't heard with a regular wedge face.
Thanks to all that gave input.