Hey man, I've had the tfv8 for about 3 weeks now, graduated from the v4. I Can honestly tell you flat out i've had no leakage from the quad coil that came with it, I haven't tried the rba yet aside from removing the fused claptons and placing transformer coils in them. But I did test out the Octo-core and had no issues from it either. The only coil i ever had any leakage from on the v4 was the triple clapton RBA, and that was usually my mistake from not having enough cotton in the gaps. And of course the top became really loose after about a week and a half, which caused it to flip open randomly. But i haven't had any of these issues with the tfv8 full size.
Edit: I just talked to a buddy who has a crown and his leaks worse than my v4 he says. So you might want to reconsider or do more research.