Wait, to be clear, are you saying the Tivo will work better with the Suggestions turned off? I recently turned my suggestions off since I was getting the Today Show, but not Good Morning America (I pretty much only watch ABC News) and some latino film festival, but I am neither Latino, nor do I like film festivals. I also do not currently have any viewing habits that would indicate that I prefer either.
I agree that there have been some winners in the Suggestions, but more often than not, I simply delete the excess shows. I do know (or at least I am operating under the impression) that the Tivo unit will operate more smoothly in the long run if you DO NOT utilize the Thumbs Up/Down feature. Since (very basically) those all point back to a database table deep inside the AI, the fewer the entries and data fields, the smoother it should run. It already gathers your viewing habits from shows that you specifically record or watch. So thumbing up/down only further reinforces your habits with the AI and speeds up the unit "learning" about you and what you want. This does not necessarily speed up the unit overall, or so I have heard from people smarter than me...