To cut dendro keiki or not to cut dendro keiki

[Massica]

This is one of my two lovely dendros below.

At the moment it has two keikis and two new canes. The research I had done told me that I should wait until the keiki roots are a minimum of 2 inches long before removing the keiki and transplanting it. However, I am having a problem in that the keiki roots have stalled at about 1.5 inches and have formed sad looking black tips, which you can see in the closeup shot of the roots.

Additionally, the plant seems exhausted from maintaining this huge keiki, and doesn't seem to have the energy to work on one of the new shoots, and the other keiki, which is puny in comparison now.

So, is it time to cut the apron strings? Also, other than being careful when cutting, treating the wounds, and not watering or sunning the newly transplanted keiki for a while and treating with root hormone to promote root growth, is there anything I need to know about transplanting a keiki? This will be my first one. Right now the mother plant is in coconut chips and that's what I am planning on putting the keiki in. Good idea?