Maybe more than you think. But it seems to me installation trumps technology in this case. The cheapies come with bracketry that is basically worthless on old lathes, so there’s a lot of fabrication required. Are the DROPros kits more complete? That might make it worth the cost for some.
But I don’t think what they sell are Newalls or some other industry-grade maker, and I’d hate to think that under the skin it’s the same stuff as the cheapies. I have no idea if that’s the case.
Rick “installing a cheapie on his SB 14-1/2 at present—learning lessons and more in due course” Denney