Hello everyone. I'm both Lutron as well as a Savant dealer.
No one mentioned Lutron's amazing iPad app. It's very intuitive and clean. If all you really want to do is control your lights from your iOS device, you can't go wrong with their app and Radio RA2. I'm not familiar with all of these systems but, Savant uses I.P. control with RA2. It's FAST, and it's full featured. Best yet, it doesn't require an RS-232 cable be routed to the repeater assuming you're already connecting it via Ethernet.
Savant is overkill if all you want to do is control your lights? Maybe... but, out of the box it does so much more and with nothing more than their host controller you can interface with IP controlled items without purchasing another piece of gear. Their iOS interoperability is amazing... pair that with a $99 Apple TV and a $299 Logitech Squeezebox Touch, you have control of streaming media with full album art, volume control, multi-zone control from up to eight iOS devices. The App is $10 (per iTunes account - not per device!) There are no monthly or annual fees. It's the only control system that actually gets better with age.
Don't give up on it just because someone says it's expensive. Would you buy a Mac Mini server and additional software do build a DIY control system?? That's about what the most basic system costs. Of course, we can also do 144 zones of distributed HDMI if you need that
It's a little more expensive though.
Let me know if I can help!
-Matt