Huh. Weird. Showed on my Chrome without any hassle. (The redirect from '/eng' (without the /) did come quite hesitantly, but apart from that...)
I've disabled both the complete .htaccess and single arguments within (for both .htaccesses, just to be thorough) and tested by fetching the url with Google's Webmaster tool (which tagged '/eng/' "unreachable" when I tried that yesterday, but had no porblem with either '/' or '/shop/').
No change. Well, except that "unreachable" turns into "not found" when the last rewriteRule in root goes missing either way. But that was to be expected.