The top one has been on here before you can see it work I used another block on mine about 18" from the cutting head to stabilize it. The first block I tapered the hole and it actually compressed it and makes a nice finish....(if it doesn't get hung up) Takes some skill to get a steady feed, if you feed it crooked or wobble it shows up in the shaft.
The second I found in a woodcrafters mag for making chair dowels. Added a block on it to stabilize the shaft after it is cut. Feed rate is slower on this one but the finished product has a higher success rate and less waste. The round bit has a milder attack rate than the straight bit and is more forgiving and turns easier. I can just pull the shaft on through with the round bit which doesn't require shutting the router off and driving the shaft out, thus faster cycle times.