i had retarded amounts of bands in my hair for a month. my dreads are fine. none of them got stuck in my dreads, none of them melted into my dreads. they just look stupid.
I had bands too for aaaages, like 3 or 4 months, they were fine 0.o rubber only 'melts' over yeeears!!! I think the bands are good at the roots, to keep things together at the beginning. I just realised they looked really silly xD But meh, dreads do for the first few months xD So do whatever you feel you are comfortable with If bands are available, use them
one of my friends keeps bands on his roots. to keep the frizz away. he likes locks that are all symetric and shit. not my cup of tea, but what ever