I have a Unicomp PC122 and it feels solid, but it sounds a bit like late IBM, much more than 1980's IBM. I heard the newer units are heavier, but I don't know much about that - I suppose they might be using a heavier steel plate, because changing the molds would be both ridiculously expensive and would invalidate their claim to be building original IBM keyboards.

In any case, the layout is more important than key feel (unless it's absolutely terrible) - for many machines you NEED those keys and, if they are in the same positions than they used to be, the experience is a lot better.