It seems both suffer of blue dot. It seems Mitakon is sharper in the center and blurrer in the corners but RJ is less sharper than Mita in the center but it is more sharp in the overall. I read Mitakon has some color issues Mitakon is a bit more expensive than JR and built quality seems to be better than JR. I'm also worried because Mitakon has another Speed booster in the second version of the product and EF-MFT speedbooster is just in the first version. Should I wait? How much better is the second version compared with the first one?

I'm quite confused about this two Speed Boosters. I'm going to use it mainly with a Kiron Kino Precision 28mm f2 and a Helios 44-2 58mm f2

Please, could you give me your impressions and final thoughts about this two lenses?

Thanks in advance