I’m reverting to the old theme to see if I can fit some of the new features in it.
I agree the new theme was too whitespace-heavy, and comment nesting was not working out as well as I’d hoped. I haven’t been able to figure out how to get rid of the huge right margin on comment lists, which is the misfeature that annoys me most. By contrast, the serif font would have been easy to fix.
A significant reason comment nesting wasn’t working for me is that the administrative page doesn’t do it even when the main theme does. Thus, when commenters reacted naturally to the nesting by leaving out quotes, I could no longer follow threads.
The main reason I changed themes was to be able to support modular theme widgets, which is the newfangled way in WordPress to lay out sidebars and footers. Also, I was beginning to fear that changes in the underlying WordPress engine would break my theme, which is a custom variation of an old one called “Steam” from the 2.x version. (I changed it to be flexible to the browser size rather than having a fixed bounding box and padding, a design style I hate for both practical and philosophical reasons.)
Now I’ll try retrofitting widget support into my old theme (I call it “Live Steam”; the new one was a stock WordPress theme called TwentyEleven). Or, I might try finding a theme that already supports widgets and has a similar look and feel. The management regrets any inconvenience.