This may come off as harsh, but I really do mean it all as constructive criticism. As always, it's your website and my advice is free to take or leave. That said..
The color scheme is very feminine. Looking at sites like okcupid and eharmony, match, etc., you're better off using a gender neutral tone. Here is a resource for the
psychological effect of different colors. I just know as a guy I wouldn't be caught dead using a pink dating site, whereas women are not adversely affected by a blue design (blue is used commonly enough to be considered a gender neutral color).
The logo needs work as well. The concept of being "roped" might appeal to a rural/cowboy aesthetic, but to a higher intelligence crowd it could come off as patronizing or demeaning. The rope squeezing around the letters "IQ" is also an effect commonly seen with branding for overweight demographics, which is probably not a connotation you want for users to associate with your site.
In at least one of your mock-up designs you incorporate math formulas and science diagrams into the background, why not consider a logo based around this concept as well? A logo designed to look like an element from the periodic table of elements could work very well.
I noticed in all 3 mock-ups you have "current users online" listed after the "how to sign up" section - I would consider switching this. If I was a prospective user, I would probably want to know what other users are like (what I'm getting myself into) before being told how easy it is to sign up.
Along similar lines, all your stock photos are of models/people that are probably appreciated for things other than their IQ. Your target demographic is probably looking more for academic/nerdy attractive people.. not ones with surfer tans and popped collars.
Last, the 'quick search' is anything but. Looking at other dating sites, the 'quick search' is usually limited to 3 or 4 fields.. the advanced search has the rest of those options. A person should at most need to know gender, age range, and location. The quick search should assume basic information such as sort by location and then IQ. If the user wants to search more in depth than that, they'll have no problems clicking on another link (and earning you one more chance for ad revenue, in the process).
That said, your graphic designer friend did well with the overall feel of the site. Rounded corners, spacing, and graphics are all fine - though I'm a bit confused about the footer art for design #2. If I'm not the only one that thinks you should make these changes, and you follow through with them, then you should be in good shape.