- One thread for multiple GPUs with a very nice overview and configuration interface
- Automatic restarting of GPU threads
- Better LongPoll/NewBlock detection (tried it recently with one of the new *Coins, with blocks coming in every few seconds)
- Less than 0.1% stales, compared to 0.5% for Phoenix (at least with my miner/pool combination)
As for overclocking, atitweak is by far the simplest and most effective tool (https://bitcointalksearch.org/topic/new-command-line-tool-for-overclocking-ati-cards-linux-25750).
If you decide to give up the nice graphic environment, there are truly much better options.
Good luck!