I put a dynamo hub and lights on my bike. The Cyo Prenium is not as brilliant as my Cygolite Expillion 700. Having said that, the Cyo is completely adequate for my commuting needs. On my maiden voyage this morning I still ran a Cygolite Hot Shot in addition to the B&M Topline Plus. I'm sure that I would be just fine without, but I feel better knowing that there is a 2 watt blinky on my backside.
I did not feel any additional resistance with the new hub, but I'm fat and slow so that shouldn't surprise me. I like knowing that I have light no matter the status of my batteries. Perhaps after I get accustomed to the new system I won't feel like I need the battery backup.