Entry 5 is easy to read, and stands out. Readable at a distance - which is VERY important. Nice integration of a creative element (star) in lieu of the dash between E and M. The solid red bar may be a bit too dominant - as a non-informational element. It adds needed balance, but seems to catch the eye as much, if not more, as the company name (distracting). Not certain about the gold color in the star. I like it, but not sure about shade. It also adds a third color, so it adds cost to printing. It may be needed and worth while, but just what to make sure it makes a meaningful/needed contribution.
Entrys 1, 2, 3 are not much different from my current style.
Entry 1 - Yellow text will hard to read on white background. Entry 4 - Font is too crowded.
More than a simple letterhead, some uses for the logo will be a large scale web splash page, as well as large format printing on a trade-show backdrop (5 foot wide). These uses will with require sufficient "glitz and sparkle" to hold attention and look professional up close. This may mean lofting the elements in some manner, and perhaps giving them a glossy effect.
Our customers will identify with clean and flowing lines. Aircraft have gobs of sex appeal, bright colors, highly polished, organized, and tidy. They are high-tech, but they are also very romantic.
Thanks guys for all your efforts. It's truly appreciated.