At what size do you see this being used?

I think the problem is visual consistency. If you are going to do the x thick stroke serifs, inside that way, the other serifs would need more of a relationship to that. So the
serifs on the thin stroke of the x, the i and n would need some relationship...

I agree with you the first is more natural. I can't really see a reason for the second option, whilst the first looks more balanced and less attention-grabbing. The other letters have normal serif patterns.

Thanks guys :-) I'm gonna take the first.

I wonder if (in the top one) the gap between the inside serifs at the top of the /x/ is too close.

Suggestion: make two different typefaces or two different weights with this. If you manage to derive an alphabet from the aesthetics of the second, you could use it as something in between regular and italic. See as well this thread: http://typophile.com/node/64298