When investing mid day (U.S.) through periods of low volume and very low volatility I have heard experts say never to exchange since the market is too readily and commonly manipulated. Does anyone have experience with this?

I would love to exchange up to $100/pip ($100 for every point of market motion ) and am wondering whether that could possibly create a goal in this giant market. If so, would dispersing the trade over a couple of different broker platforms (non-ecn) be a safer way to trade? I have heard this is typical for individuals trading with larger amounts. Just not sure what larger is.

Rex