I have been using a Richmond (Rheem) power vent for several years and I really like it. Since I installed mine, the venting requirements have changed a great deal. I have to use 4" pipe and was limited to just a few feet. (I don' recall exactly how much) Today, you can use small pipe and run it quite a long distance. There are two negative issues that I can see with a power vent. They cost considerably more than standard vent models, and if you remove the old vent and close the hole in the roof, you are pretty well committed to stay with power vents or go to additional expense to reinstall a conventional vent. Those may or may not be serious issues for you, but I think you should be aware of them.