The Microlux is really the Seig C3, all the others (HF, Grizzly, Enco, Cummins etc) are Seig C2s either models 200 or 300 based on bed size. The only difference between the 200 and 300 is bed length (200 and 300 mm respectively). The C3 adds larger motor, better electronics, larger bed (350 mm). Micro-Mark is currently the only authorized distributor of the C3 in the US.
The leadscrews on the compound and cross slide on the C3 are 20 tpi which allows for exactly 0.050" per turn of the hand wheels. The C2s have metric threads.
Seig re-designed tail stock which has a cam lock like most wood lathes rather than a nut that you use a wrench to lock the tailstock to the bed.
I believe that the C3 has a slightly heavier casting on the bed in addition to being longer.
The remaining parts of the C3 are interchangeable with the C2 which makes getting spares easy.
What the folks who rebrand the Seig lathe bring to the table is primarily the acessories like chucks and steadys.
All of these lathes (and some larger ones like C4 through C6) are made at the Seig Industries factory in Shanghai. The same is true of all of the smaller milling machines which are rebranded Seig X1 (Grizzly G8689) through Super X3 (Grizzly G0619). Similarly multi-function machines like the Seig M6 are rebranded (i.e. Grizzly G0516 combo lathe / mill).
