I have owned both cartridges. The MC-One Special was an upgraded, older MC-One. It was upgraded as part of a re-tip, for no additinal charge.
IMO, the two cartridges are roughly equivalent, overall, as far as general sound quality level. The MC-One S has SLIGHTLY better resolution, but the Two has the advantage of the higher output, which means lower noise floor, and better dynamics. It has a lot to do with the phono pre that you will be using, and the overall gain structure of your system. But, IMO, unless the higher output causes your volume control to be run at an unusually low setting, or there is the possibility of overload of the phono stage (rare), higher output is better.
By having your MC-Two retipped, you will take advantage of VDH's latest thinking re geometry, and may even be able to request fine-tuning and compliance to match your tonearm. Last, but certainly not least, you will have a cartride that you absolutely know has zero hours on the stylus and suspension, as opposed to the inevitable uncertainty of buying used. A no-brainer IMO, get the MC-Two retipped.