Model Name shows M512a-H6 but technical details shows as M51a-H6 (model without upfiring speakers). However, customer questions/answers seem to indicate that it is indeed the M512 model. I am working on Best Buy price matching, but they seem to take issue with the Amazon shipping time of 1-2 months (BB considers this as unavailable/backordered).
I know the Vizio soundbars seem to be very hit or miss, but media reviews for this model seem favorable so far and there are very limited actual user reviews. I did have the SB36514 previously for a couple of weeks and ended up returning it due to connectivity issues and having to power-cycle, so I am hoping that this model does not have those issues.
Edit: successful price match at Best Buy for $299.88 with local pickup (should be ready today and I was able to apply a rewards certificate)
https://www.amazon.com/VIZIO-5-1-2-Theater-Sound-Dolby/dp/B08TV6GJF7
https://www.bestbuy.com/site/vizio-5-1-2-channel-m-series-soundbar-with-wireless-subwoofer-dolby-atmos-and-dtsx-dark-charcoal/6446231.p?skuId=6446231