The results are in and so far, by mere observation, the all-natural compost is yielding the best results. The most evident is on my potted Moso (Phylostachys edulis) bamboo. I counted 13 new culms that burst from the ground, that's compared to my other 3 potted bamboos that just had Osmocote applied. Now granted there may be variations in species that may influence the results (like time of year they shoot), but looking at my three clumping bamboos that I also applied compost to in December, I am seeing similar favorable results. That said, this experiment has brought me to the conclusion that going all natural in terms of fertilization seems to yield healthier more vigorous plants.
One a related note..... yesterday, in an effort to "heat up" my compost bin, I purchased a box of blood meal (13-0-0) from the E.B. Stone Company and applied it to my bin. I also applied some to the soil of my bamboo plants. I'm hoping the shot of nitrogen, which bamboo can't get enough of, will really encourage new growth and green the plants.
Time will tell.....