Please discuss.  I've been kicking around the idea of picking up an EoTech for my 870 Marine Magnum.  I also need to find a solid, high-quality top rail for mounting.  I've heard both good and bad about the 870 RAS, so I'd love to hear other recommendations.

TIA

I ordered a KAC 870 RAS.  I don't have it yet but soon will (I hope).

I'm putting an Aimpoint on mine but I have an EOTech and will try it.  I'm sure either will be great.  I'll get back to you when I've got more info.  

I think it works great!
My 870 has been used in this configuration for a couple defensive shotgun classes. Everyone in the class thought it was a pretty cool setup. It is VERY fast, and slugs at 70 yards were no problem.
As for the mount, mine is a Da-Mar purchased from Brownells
It has 6 holes that need to be drilled and tapped. They secure the mount to the slightly thicker area of the reciever. Right now my 870 is getting a set of Track-Lock ghost ring sights installed as well. They are tall enough to see over the mount when the Eotech is removed (incase of optic failure or my instructor painting the targets red ).

Cool, QuinlanV!

When sighting, do you use the dot or the large ring?  I imagine 70 yd slug shots use the dot but how about the other shots?

I ordered the identical forearm, too.  Any trouble with binding after installing yours?