Alba is the fastest growing form of Ludisia discolor, and when it's happy it will grow like crazy. It's not particularly picky about substrate... it just likes humidity and substrate to grow ON. Not "in", ON. Jewel orchids are ramblers, and all you need to do to "plant" them is to just drop your cutting/stem onto a substrate that stays moist and it will grow roots down into it and be happy. Putting the fleshy stem into substrate will cause it to rot in most cases and can rot a nodal section, or the whole plant.
ABG is supposed to have the various pieces of substrate stay moist, but chunky enough that there is plenty of air between the pieces. This allows the roots to always have access to moisture without compaction that will cause lack of oxygen to the roots and will rot plants that are sensitive to wet feet. Very handy for touchy epiphytes and what not... of which the jewel orchids (barring the stem thing mentioned before) is not. I've had them grow on compacted peat (read - mud) before by just tossing a cutting into the tank and letting the plant figure out where it wanted it's roots. It's why jewels are so good in the soggy messes that many frog tanks end up being.