I reached out to Sig below is the response. Great customer service. I have per-ordered the Vortex Viper
Vortex Optics - Viper Red Dot 6 MOA Dot
ROMEO1
But now i am going to cancel the order. As I think the Sig Romeo 1 is worth the extra money. I am going to compare both but I like the features of Sig the only thing I like more about the vortex is that you can actually turn it off and just use the iron sights. With the Sig I will have to just have to take out the battery.
Thanks for your interest in the ROMEO1 pistol sight. As long as you have suppressor (tall) sights on your M&P Core yes it would be a true co-witness. If you have standard (low) sights it likely will not fully co-witness. You also will need to use our SIG adaptor kit (plates).
Along the talk of the ROMEO1, look into our RX series when it becomes available (we hope first part of 2016). This is a great value because you can get an entire new pistol, installed R1 on a custom-milled slide, true co-witness at the price around what you may pay for competitor reflex sights and mounting kits. It is like getting the pistol for free!
Sorry, I meant to mention that in first reply. We anticipate to have the ROMEO1 adaptor kit sku’s available in late January. However, this may move as we get closer, but definitely our goal. As far as ordering, you should be able to pre-order with a local SIG dealer in your market; go to
Dealers | Sig Sauer
R1 with Mounting Kit in Granite #SOR11005
R1 with Mounting Kit in Black #SOR11006
Kind regards,
Craig
Craig Pfeifer
Sales Operations Support Manager, Electro-Optics Division
19861 SW 95th Avenue
Portland, OR 97062 USA
D: 603.610.3879
C: 503.936.4385