I have not handled the Remington mount, but in general if I am going to use a removeable mount on any kind of gun I start by looking at what B-Square has.
In the case of the 870, B-Sqaures saddle mount is good because it mounts to BOTH sides of the receiver. The screws go through one side of the receiver and thread into the other side of the saddle. Very secure and can be removed and will return to zero. If the gun is dedicated, put lock tite on the screws. I trust this mount. If you already own the gun and barrel you want to use, go this way. cost wil about $50
www.reliablehost.com/bsquare/shotguncant.htmlEven better would be to get a dedicated barrel like a Hastings or Remington with mount on the barrel.
Third, you can drill and tap receiver and add a piece of weaver rail etc.