Oddly, Miller chose to produce two MVP plugs for 115VAC (#219-259 & #219-261), even though there is virtually no advantage to having the NEMA 5-20P option, as the NEMA 5-15P plug will plug into a typical NEMA 5-20R receptacle.
So why only one plug for 230V (#219-258)? Furthermore, the NEMA 6-50R receptacle is not typically found outside of welding shops, or specific farm & industrial locations. It does make sense to provide a NEMA 6-50P MVP plug for larger welders that are going to spend most of their time in a dedicated welding shop location. But the primary advantage of the Multimatic 200 -- in fact, I would say its main selling point -- is that it is designed as a portable lightweight unit designed to go "to the job." But how many construction or maintenance job sites are going to have a NEMA 6-50R receptacle available? I've never encountered one. Even the typical construction site generator doesn't have a NEMA 6-50R receptacle. What are commonly available are NEMA 6-20R (straight) or NEMA L14-30R (locking).
This means we must make our own adapter cord, or we must limit the Multimatic 200 to 115VAC use. This defeats the entire purpose of the MVP plug and diminishes the portability, compactness, and versatility of the Multimatic 200. And let's be clear: making your own adapter is not cheap: just the NEMA 6-50R connector alone for making your own adapter cord will run $50 to $100.
None of this makes any sense. My suspicion is that the MVP was developed for Miller's other product lines, and that it was then carried over to the Multimatic 200. Perhaps not as an afterthought, but without consideration of the Multimatic's objective as a stand-alone roving welding shop.
So is Miller going to expand the MVP plug options? I certainly hope so.