I would not buy either. Single Tonearm: I want a removable headshell allowing a small collection of cartridges: Stereo; Mono; MM; MC; New; Vintage with otherwise unobtainable cantilevers. I prefer the option of a second tonearm, to start, or in the future if you want.
a Mark Levinson 515 shows up on VPIdirect, they call it a Trade-In, NOS, for $5,500. Web page is confused, You would need to call and clarify, if they have one, if so what cartridge comes with it, or have them give you a few options.
https://www.vpidirect.com/products/levinson-515-trade-in-nos
they are both made by VPI, however, they have differences, I agree, go with the company that makes it, however, buying an ML from VPI, the guarantee would come from VPI, so I would choose the ML due to their use of a Tonearm with two important differences
1. no exposed wire that make’s a random amount of ’pushback’ on the arm (thus randomly effecting anti-skate), ML is all internal wire, soldered within the unit with RCA jacks.
2. anti-skate adjuster exists on the ML arm
other differences, integral motor supply, ... see this review
I want a real dust cover for when it is off, I don’t see one, perhaps an option is available

