I could be wrong but I don’t think you’ll get much magnification with those lenses. My Raynox 250 seems to work much better with at least a 100mm lens behind it, and 200-300mm would be even better. 

In really bright light, the OVF is really nice to have. I could live without it, but I'd miss it. 

At 16x20... maybe. It depends on the subject and how you use the lens. The F's lens is definitely at its weakest very close and wide-open. If you often shoot very close, the new lens could make a significant difference for you. If you like to use the lens wide-open, the new lens probably renders somewhat differently; sharper, but also with different bokeh and local contrast. Which you like better gets pretty subjective.  Personally, the only feature the V has that I really wish the F had was the ability to simultaneously record uncropped RAW when the digital teleconverter is in use. I just shoot twice to get around it, but it would be nice...  Whether those are "great advantages" is really up to you :). 

OK, thank you for your test. Two of my friends have had the same issue than me. I will reset my body and try again. If the issue still exists, Fujifilm Support should help.  

Try starting at this link: https://fujifilm-x.com/global/support/download/firmware/cameras/x-t30-ii/ The link is the next from this starting point: https://fujifilm-x.com/global/support/download/firmware/cameras/