Some people make gravel work but I agree: it's a more difficult way to go.
I have tried planting before adding the cap and it's just a complete mess. You'll end up burying some plants by accident, and in trying to save them you may end up ruining your sand cap. Planting through the cap is quick, easy, and mess-free; why improve an already painless, effective technique? The one exception where it might make sense to plant as you describe is for plants that already have very extensive roots, like large swords or crypts that are already a few years old. Sometimes I have a little trouble getting all all of the roots of older transplants down into the cap, but I still do it because the thought of carefully adding the cap around a plant stresses me out too much.
Last edited by Bananableps; 12-22-2017 at 03:13 PM.