I typically like the aluminum cased Dale resistors for something that big, power wise. You probably wont get a much smaller package though.
Yes they're there to mimic the load (ie resistance) of the incandescent bulbs so the flashers flash at a similar rate. I ran LED lights on the rear of my superduke (with incandescent fronts) and the flashing was faster but i didn't mind. The integrated tail light on the old Z1000 actually had a module that replaced the flasher relay.
There are flasher relays for cars that are load independent, they always flash at a set rate, but I'm not sure you could directly fit one of those relays on a bike...
Yes they're there to mimic the load (ie resistance) of the incandescent bulbs so the flashers flash at a similar rate. I ran LED lights on the rear of my superduke (with incandescent fronts) and the flashing was faster but i didn't mind. The integrated tail light on the old Z1000 actually had a module that replaced the flasher relay.
There are flasher relays for cars that are load independent, they always flash at a set rate, but I'm not sure you could directly fit one of those relays on a bike...