Some of you already know about this adapter. It works with both Apex 1 and Apex 2 models. It will fit the T9 / 9.1 series stock barrels as well as Lapco's Str8shot. $17.99 seems better then electrical tape.
FS round fins will catch/cut the rubber tongue in the apex.
For regular paint though, most definitively. With the screw on adapter it's easy to change on or off if you are planning to use paint or FS that day.
As to the DeadlyWind adapter, that's for attaching to the DeadlyWind thin walled carbon fiber barrels. It's not a generic adapter tip. I've used it on my brother's CCM T2 w/DW barrel. It's a very tight fit. You won't easily get that onto a barrel it wasn't designed for.