I am familiar with them and I went to their link to ensure they had not developed something I was unaware of. The 3 videos on their site that I watched were all powered by power packs. Power packs are definately productive and have their applications but your average contractor does not need a power pack. Please don't get me wrong. We build power packs too, and very good ones ( I work for Fecon so consider my bias) but power packs are only for the people who need to maximze productvity in larger diameter material at all times.
If you need a power pack, great! That means you have a lot of work and need to get it done as fast as possible. Go to other manufacturers for a quote if you must but be certain to compare Fecon excavator mulchers and Power packs when you are shopping. I will be happy to explain why it will be beneficial to you, even just to compare products, productivity, and prices.