Here is what I 'think':
1. Think about what makes the Think6.5 originally: its DNA, features, why the name Think. Go beyond the angle, the layout, and Descartes quote.
2. If we deviate from the core DNA and signature that makes up Think6.5, is it worthy of to add V2.0 to the name or is it time for a new name.
3. A logo should be consistent. Sagi Haviv, the guy who design many iconic logos (National Geographic, Chase, NBC, etc) have said that a logo is identification, not description. Using the logo consistently help identify what "Think6.5" is. When you change a logo, you risk losing brand identification and recognition. In trade off, you gain ability to improve the brand messaging.