I think the prospect of getting rid of the bottles and the possible battle it may start is what makes so many moms afraid to switch.
We forget our kids are more resilient than we give them credit for!
With both of my boys, we started practicing with the sippy cup from about 9 months on. At 12 months, we literally took it away when we ran out of our last can of formula. If they wanted to drink, they were going to drink it out of the sippy cup. Since it wasn't this foreign concept to them, there was no problem.
There was no protesting, no crying, no crabbing, and they even transitioned to going down to bed for the night without the bottle.
Think about it this way - who needs it more, you or the child?