The numbers are (for example) are still bold therefore the <span><label.. does look dim in comparison. I would not make the numbers bold or the <span><label.. but that's just me. If you don't like the look of it then go with it being bold. In the end, the eye should be the final judge.
I personally like the way you have it in your first screenshot. It focuses the eye on the range of answers instead of all the answers. IMO it will help your survey-taker to focus their brain on their options as well. However, I think it's a matter of personal taste. I've seen it done both ways. Generally, though, bolded text is only used for emphasis, not for visual aesthetics.
I would recommend removing the word "Article" at each end, as it's redundant. The question asks you to rate the article, to that word is implicit. The user just needs to know which end is which, and "poor" is enough to indicate that number 1 is the low end.
As for the bold, I'd be inclined to remove it and perhaps use italics instead, to distinguish it from the questions themselves. Whatever is bolded is most important on the page, and "poor" and "excellent" are not the most important text. They are really just little asides to clarify what the numbers mean.
If anything, I would bold the questions, as these are really the most important parts, and bolding them would help the eye distinguish them. (You know for sure where each one starts and ends.)
Any thoughts on the latest screen-shots that I posted?
They both look OK to me, but I can understand why you wouldn't want too much bold at the top of the page. You could perhaps lighten the color of the questions to compensate (a slightly lighter gray, for example).