Considering these helmets. Searching didn't turn up much. Planning to use this on a WR250R and I have street bikes/helmets so looking for a 90+% dirt helmet for TAT, etc. From what I can find, both are excellent helmets, but many people rave about the venting of the F4. Is the venting really that much better than the VFX-W? Anyone used/tried both and can provide some insights? Thanks.