I like this concept. It's clean modern and easy to work with. Of the 4, I like the proportions of #28 the best but I'm not thrilled with the greenish yellow color. Maybe Red and Black or Orange and Black?
It may just be an optical illusion or my screen but are these submitted on a slightly tinted blue background? If so, I'd like to see any revisions submitted on plain white or other solid background since the gradient background will most likely not be part of a sign or other limited color silk screen printing. If it's just my eyes playing tricks on me, please disregard.
Are yes no need to consult on optician they are submitted on a tinted blue background as my template document has this setup that way (an old habit of mine). here's some more proposals for you to look over.