I have never had the chance to try the Phantom II. Recent posts make reference to it and the Synergy being similar in flight characteristics.

Can people who have had both tell me how and why the Phantom is better?

I would not say they were similar at all other than they are both arcs- in my experience the synergy like the charger 2 is "early" to be grunty whereas the phanny2 likes to get up and running and then will build and build on apperant wind. the phanny was really good in the buggy for me and really like to fly on the edge of the window- whereas my experience with other arcs (venom,synergy, c2) tend to sit back a little and have more grunt more quickly which helps when trying to go vertical

I would agree with Fly's assessment and would add the the Phantom 2= better upwind, better glide in jumps than the syn. Gust handling is about the same, turn rates about the same.

I agree with your opinion

Phantom II is amazing upwind and its optimum line is more upwind than other arcs. I too agree the Syn is more grunty and not as amazing upwind.

I had a chance to run with Steve Bateman and Phillip Chase on Ivanpah. When we were all powered up, I would get across the lakebed at the same time and be a hundred yards upwind. Some runs I was slightly underpowered on a 9 and I thing they were on 10m Scorpions and Venoms.