hi Mike,
If 4.9mm is what you are after then keep going until your bees are drawing it to a good standard, 5.1 is one of the stages the bees will build but keep at it until you have your 4.9mm. use any thing you can that isn't harmful to your bees and doesn't leave residue in your new wax to keep Varroa as low as you can as you are regressing, rotate the old wax out but leave the drone in the hive but move it to the out side frames.
i did wire with foundation-less frames but find it easier to run one of the bottom bars down the centre of the frame, i think it depends how much time you have but both work.
you can't make a conclusion about 4.9mm working/helping if you give up at the 5.1mm stage of the regression, so keep at it and best of luck.
TC