My good man,
Obviously, if you go with Trading Dixon out it involves getting Hale, or swapping Dixon and Brown, and having a donut on your Forward bench. Given you have Rohan, Impey and JKH, you may just be swapping this weeks problem for next weeks problem. My preference would be Dixon out, but that fragile Fwd line with Brown in it worries me. That being the case, unless you have done some sort of Fwd correction with your other trade, I think it should be McEvoy. Yes, it still leaves a Dixon donut on your Fwd bench, but he's more likely to play sooner than Brown. Maybe ditch both Dixon and McEvoy?
If you don't have a strong opinion as to WHO the best Rucks will be, I'd go McEvoy to HMac. when in doubt, go to the cheapest option with good JS, that can score points.
Good luck