We've had about 500 people come through the 4th in whats almost a year. The vast majority hated the melee even if they never played NW. Bad melee, and repetitive gameplay is the number one reason we've had for people leaving.
For the ones that did play NW they went in expecting the minimum standard of melee to be a copy of it. Any improvements would be grand, then after giving linebattles a chance they just leave (I've followed up with our websites member profiles and the overwhelming majority have not played Holdfast recently).
But seriously its getting hard to keep people around. We have people who use the musket in GTAV more often than they play Holdfast at this point.
My only suggestion now can be that we would be ok with a clone/exact copy of NW's melee system. Won't even need any improvements.