I came to this late, but I have a little different perspective.
Sammy is on mostly regular cups, I'd say 80-90% of the time, otherwise he uses a straw cup in a restaurant or on the relatively rare occasions when I give him water in the stroller, car seat or walking around. He has never had a sippy.
He is in a montessori daycare where they also do not believe in sippys for the reasons above, as well as because of the general montessori philosophy (haven't read this so I may be misquoting) that children should be given the opportunity to do things for themselves as soon as it is developmentally possible because they get such pride from these accomplishments.
When we started solids, we gave him sips of water from a small regular cup with the food. Around 11 months the daycare starts the process of weaning from bottle to cup, and they ask you to work on this at home, and not to introduce a sippy. It took 2-3 weeks to get him drinking from the cup (with me holding it) well enough to stop the bottle, which was right around his first bday. It really wasn't hard to do, I just offered him the cup at every meal.
Over the next few months, he progressed to the point where we can place a small regular cup (we actually use a heavy-bottomed juice glass) on his tray, and he will pick it up, drink and put it down. Sure, sometimes he'll spill, but there's no more than a few oz in there, and it doesn't run off the tray or anything. He tried deliberately shaking the cup exactly twice, to see what would happen, and when the milk splashed him in the face he cried, I cleaned it up, and he never did it again.
I didn't introduce the straw cup till he was really good w/ the regular cup, so that he wouldn't develop a preference for it. I don't generally give him liquids when he's walking around the house etc, since he has a meal or snack every few hours and some sips of milk before and after his nap, he gets plenty of liquids. As I said, he uses the straw cup if he does need water or juice in the stroller, or in a restaurant.
And BTW, Sammy is a regular average baby in terms of motor development, even a bit behind the charts. The other babies in his daycare all use the cup very well also.
So if you were at all interested, I would say you can go ahead and try the regular cup.