I would just like to note that up until this morning we had some pretty bad issues with the E3D hotends, we pretty much had to run them 20 degrees hotter for all materials to get them to extrude properly, this was not the hotend it was our extruder springs! make sure you use the correct springs as this makes a significant difference.

For people in NZ these ones are great (thanks Makershop)

http://www.makershop.co.nz/hardware/ExtruderSpringSet

As a good measure the spring coil wire thickness is about 0.81 mm, in terms testing them yourself they are quite painful to fully compress with your fingers.