I finally found what I was looking for ... I actually started the thread myself back then, and one of the answers I got was this (emphasis mine):
Yes, you can choose to only watch the episodes with the original effects. You can also choose to listen to the mono track with (for the most part) is about the same as the original sound mix as the originals.
However, there are a couple of episodes which incorrectly have the new opening credits, even when you choose to watch the original version. The rest of the episode is fine, just the credits got screwed with.
You can also listen to the original sound mix over the new effects, so you never have to listen to that re-recording ever, even if you're in the mood for the new footage.
Can anyone confirm or deny that thing about the opening credits?