Personally I think I would go with this
http://www.cnc4pc.com/Store/osc/product_info.php?cPath=64&products_id=338 I have never tried either that or the Gecko but the differential encoder inputs, fully adjustable following error and USB connectible tuning would swing it for me.
Geckos are good drives as well for smaller machines but just a bit lacking on the above features.
Hood