I have also thought about putting back on my original stock. I know I should have shot the shotgun before changing it. I wish I did because that would have gave me a idea of what it needed and what it did not. Well that's to late, it would not be much to just switch out stocks, just about 10-15min. Here are some pics of my finished 870 with the new light mount. Here is also a pic or 2 of the same shotgun when I first got it.
Yeah it's always a good idea to shoot you shotgun as it comes before changing things. It looks like yours came with a Speedfeed IV Rear stock, actually rear and front Speedfeed furniture. If you like the pistol grip stock, and you're not real happy with that ATI, i'd put the original stock back on. I have shot an 870 with that Speedfeed stock and i liked it; it's just obviously going to be a fixed, longer LOP Stock. You mentioned maybe getting a Magpul stock too; that is a great adjustable LOP Stock and is really a comfortable and great handling stock. While it's not a pistol grip stock, it is a "semi-grip" stock; it's like the best of both worlds so to say. It is really a great stock, maybe something to consider. Just my two cents..
Gun Control Means Using Both Hands.