I listened to the MB demo with my headphones on and I have an ER1 Mk1 (which I bought used for under $200).
The ER1 can makes sounds like the MB, but it's also digital in a way the the MB can never achieve. Its effects are glitchy as hell, and send me to digital heaven. To get that sound from an MB you'd have to play it through the ER1 aux inputs. Throw in some motion sequencing and panning – which the MB also can't do, and at least to my ears, it's a different sound realm. I can only take so much of it, but I love it.
So no, I can't really say the MB sounds like an ER1 all by itself. It sounds more to me like a capable, general purpose analog drum machine, with a thoughtful design, at a totally reasonable price. Would I love that? Sure, if I didn't already have other ways to make beats in hardware. But I especially admire the manual knobs for shaping each voice. Another thing, like the ER1, there's not much in the way at staring at a small screen. As basic as it is, it's mostly right at hand. Playability-wise, that wins for me. It'd be cool if you could map all those knobs to external synths and sequence away.