Hi, I'm trying to choose the best option and can't decide. MedEl is offering 2 processors until August 2015. I have three options 1. Opus 2 + Rondo 2. Opus 2 + Sonnet 3. Sonnet + Rondo I like the third option, the cons is that Sonnet doesn't have rechargeable batteries yet. They will be released later, and might cost me around $700. Please help me?