Well, I received my new FN SLP MK 1 a week ago.
I cleaned it and loaded it up with a variety of ammo. It definitely will not take light loads such as birdshot, whether high brass, or low brass.
The new model comes with the single gold gas piston, not sure whether it was suppose to handle both light and heavy loads, but light loads will not cycle, period.
I loaded up some buckshot and slugs, it fired and cycled as fast as you can pull the trigger.
I purchased the FN SLP MK1 for home defense and as a fighting gun, so I won't be shooting anything besides buckshot and slugs in it anyways.
I probably should have purchased it when the price was below $1000, but that's hind sight now.
All in all, I'm happy with it unless it starts failing to cycle with heavy loads.
A word to the wise, if you are looking for a shotgun that shoots everything, you need to look elsewhere.
Rating: 5 of 5 Stars!