TDK VeloCD 16x 2 versions of it?

Ok here is whats up guys, i went down to costco and picked me up this burner. And when going to update the firmwire it shows on tdk'z site that there are two versions of this burner out there on the market. It appears that the one that is/was the retail box one that you would buy at a regular store or online was serial number AICDRW161040BX and had a X after the 40 on the face plate by the read speed and uses firm wire 5.32. The costco version seems to be carried a few other places two, uses a different firmwire versions 1.01 ands serial number AICDRW161040 and has no X after the 40 on the faceplate ( read speed) . Does anyone know if there is a quality differance between the two. Is this TDK'z way of cheapening up a version of the same thing to make it cheaper for costco to buy, or is this actually a whole new revision of the burner that is better/worse. I read a review at www.cdrlabs.com of this burner, but it was the non costco one. And on a end note egghead.com carries both versions, at almost the same price, can someone help me answer this. Thanks All