I’ve tried on DFV loupes at VCU’s loupes fair and actually like them the least of all the vendors I tried (Q-Optics, DFV, Surgitel, Orascoptic). While the optics themselves were nice and clear, they were extremely heavy and large for the magnification given as were the frames. The light was a bit heavy as well from what I remember. They had limited magnification options and were not very competitively priced. Out of our 98 person class, I think only 2-3 people bought from DFV. About 40-45 people bought from Q-Optics and the rest were split between Surgitel and Orascoptic.
Price and comfort are the two biggest things I looked at when I was buying loupes and with that, I found Surgitel and Q-Optics to be best. The only reason I didn’t go with Surgitel was because their frames were a bit large for my small face and I didn’t like the idea of having plastic Oakley frames (it’s actually some synthetic flexible material but I liked having purely titanium alloy frames like Q-Optics does due to increased durability). If you’re willing to splurge, then I think Orascoptic offers the clearest/best optics. But for having spent only 1200 on my loupes and lumadent light, I’m extremely happy with the comfortable loupes I was able to get.