Yep I've done a couple elk antler pens with the Easy Wood tool that has the round tip. I have the square tip one as well but I find I don't use it as much.
I've only used mine on acrylics, and then not for general roughing. It worked good, and didn't cause any problems. I've also used my local Woodcraft store's EWT finisher during "Turning For Troops", on wood (walnut), and it did an excellent job with roughing.
i have used tham at one time or another. they are the best tools i ever used they are the easyest to use and their are easy to sharpen. best buy on the market, to bad i can't afford them. just got me a small set of tools for around $60.
Turning deer antler is why I got mine. I have one of Ken Ferrels tools and it uses the square insert, it will turn antler like butter. I turn a lot of pens, wood, antler, and some acrylics, and have not have problems with it. I love it.