Aqualung owns Apeks, however, not all Aqualung dealers are Apeks dealers. (though many are).
You should be fine with either reg.
If you choose the AL Legend LX, you might consider the Legend LX Supreme since you plan cold and ice water diving. It's actually the same regulator but it's set up for colder water with a lower intermediate pressure. But it also has a nice 'mouthpiece guard' that comes with it which keeps your lips a little warmer. It's removeable for warmer water diving. It basically is a rubber guard that gives your lips something press up against underwater which helps slightly with the cold in the colder water situations. Other than the lipguard, the intermediate pressure change (lowered to 130psi for colder water), and a few cosmetic changes (silver ring on front and snowflake molded in plastic), it's the EXACT same reg. They charge about $10-$15 bucks more for the Supreme though.