As you can see, there is some debate as to the effect of B100 on rubber. If this is your only concern though, and for most people it is, swap them out and enjoy.
www.greaseworks.org can hook you up with pre-cut hoses and instructions, take you no time at all to switch to Viton.
And if you homebrew, I recommend washing. As we see here, some people feel it's unneccesary, and to their credit they run miles and miles on unwashed fuel, but lacking the means to visually inspect our injectors and whatnot very often, I like to play it safe and wash.
B20 is a great thing for 'weaning' people on to biodiesel. Not everyone's willing to take the whole leap at once and I understand that, but calling B20 biodiesel is like putiing 20% champagne into 80% water and calling it Dom Perignon.