I want to buy my third Tivo, the Tivo Edge Cable 2 TB but before using, want to install a bigger hard drive. I watched the Weaknees upgrade video. Which brand is best and what size? Are there any available hard drives that are 6 TB or bigger that can fit in the same Tivo hard drive tray? Trying to avoid external hard drive case. Also, is there a way to avoid having to format new hard drive before Tivo formats? Thank you for your help.