Hi guys! I was looking into DFV for loupes. I am trying to decide between 3.5 vs. 3.5 EF. I really liked the way their nike frame fit. So my question is how much heavier do the 3.5 EF feel compared to just 3.5? And do I have to get a specific frame in order for the 3.5 EF to hold up ok? I am thinking the nike might not cut it for the EF