While visually I love the update and will say it's an overall improvement I must admit I'm running into a few frustrating walls with the simplified formatting. Here's a breakdown:

Headers

I can understand the previous headers were a bit too large and had the possibility of being abused. I'm actually kinda surprised I didn't see more shout threads done with nothing but a single hash header, but personally I feel this is a bit extreme. I'll admit I'm personally bias because I've been used to sub-divide my sections with different header sizes, but I would very much be fan of just one more Header option that's a bit bigger, it really helps with the visuals of dividing sections (and I might not have to go into GIMP to make headers with every one of my longer posts :P)

Horizontal Dividers

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====================================================^This
Love the new one, looks really nice and all as well as giving me hope for an eventual centering option, but can I have the option for the old one too? The reason being is that without a centering option for the rest of the text the body of a longer post will always hang to the left, making the divider much less noticeable, which partially defeats the purpose. Now I'm not saying switch them back, but if the syntax for either could be decided by maybe "___" and "---" I feel like that could be a good addition.

Tables

I notice you can still use the table format to create what are effectively columns of text but with no visible lines for the table itself. Was this intentional? Is the table option going to be removed? Personally I could live without it, but neither do I see a real reason to remove it so I would love to hear the plan for it.

#Thumbnail control

Love the addition of thumbnails, but I would also love to know if there is any option to control the image used. I notice Krylhos is incorporating a thumbnail that is not included in the post itself in his Change Log post. If that's a Red privilege, ok, nbd. But I'm going to remain on the assumption it's not until I'm told otherwise and will try to find out how over the next few weeks :P.

#Spoiler Function

Yes this has been said numerous times before, and I'm sure it's been heard very clearly, but: Spoiler Functionality. I cannot express to you how happy I would be to see this in, or even a confirmation of it being actively worked on.

That's it, feel free to add any other frustrations or improvements to the CB formatting you would like to shout out guys and gals.