I'm glad everyone who bought an SR-22 has sunk hundreds of dollars into mods and upgrades. What were you thinking!? If you wanted rails, cool stocks, etc. the ISSC was the way to go. Yes, Ruger has a great platform to build and trick out but did you really buy a .22 to sink over a thousand dollars into it? Have my ISSC with Burris Tactical Red dot and shoots excellent with bulk ammo, Quad rails throughout, adjustable stock and comb, extra mags, 6 position charging handle, and true AR thumb switch for safety, not a cross bolt. Shoots out the 10 ring all day and with a solid 22 shot clip. I am happy with mine and would challenge any 'stock SR22/10-22' to shoot the same. Mossberg doesn't interest me at all. I saw a red dot on top of the carrying handle and had to laugh.
Best of luck choosing your money pit. But always consider how and why your purchase will meet and fill your needs.
At the end of the day, if your gun looks cool, but you can't hit anything, then it doesn't really matter how cool your gun looks. You still can't shoot.