Not familiar with 887, but you can't go wrong with the 870. It's very reliable. Parts are cheap. It's very easy to do you're own work on it. Many accessories available to make it to your liking. The 887 is too new to know how reliable it may be. Here's a pic of my 870 setup for a match. At home I run it with the shorter mag.
"Ex Umbris Venimus"
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Camel Trophy 1998 - Tierra Del Fuego
Rainforest Challenge 1999-2001 - Malaysia
Outback Challenge 2001 - Australia
Croatia Trophy 2002 - Croatia