I think it would be awfully easy to pierce with your needle and so if you planned on pulling you would probably be out of luck. Also unless you were going to do small designs....there is not much on those packs of floss.
I have used SoftTouch flexwire for warp thread. sounds expensive and almost like overkill but it's great to work with. you cannot pierce it and it really doesn't add extra width between beads.
I agree with Georgia - dental floss is long vertical strands. it is seemingly set up specially to be pierced while weaving.
better choices would be cotton thread, hand quilting thread, or buttonhole thread. the problem w/ cotton threads is that while they do not stretch, they are a natural fiber and begin to deteriorate over time.
another set of choices is offered by the C-Lon micro-macrame threads. these would be a real thrill to work with because the colors of the thread would influence the colors of the beads next to the warps. I'm planning to try this heavier thread for both warp and weft at some point.