How old are they? I split an older 2006 Atomic Rapture at the end of its life, it has turned out well so far (not as many days on it as I would like yet though). You’ll loose some torsional stiffness, so both those boards from what I remember are super stiff so that’s good.

You’ll want to watch out on what the core is made of, which is why the year might make a difference. Mine only had the D4 fiberglass construction along with the milled core which didn’t cause any major issues (just made epoxying a bit more of a process with air bubbles).

The newer Dreamraider’s specs say it has a FS Kinetic core (I think in the nose?). I was considering splitting the newest Alibi, which has FS Kinetic core material in the nose and tail in 2 parts with a wooden stringer in the center (where the cut would be). The atomic snowboarding rep didn’t think that would cause any issues because I wouldn’t be cutting into the tech material – if the Dreamraider has the same wooden stringer through the FS Kinetic core section it will probably be ok, just make sure it’s a thin straight cut. And probably steer clear if it’s a solid FS Kinetic core section. Also, if either has carbon stringers in the construction, I think you run a higher risk of losing more stiffness if the carbon goes from toe to heel side and crosses the center of the board. And there is the risk of ‘rebound’ from the carbon, that I’ve read about.

I’d probably recommend you split the board with the more simple construction method. If they both are basically wood with fiberglass construction and nothing high tech, split the stiffer one if you want a stiffer bc ride, or the one you like riding more in the backcountry conditions your more likely to encounter.