I seem to be nearly alone in my non-fascination with clipless pedals. I've tried two different setups several times on roads I ride often, and I've found no difference in time, speed or perceived effort.
That's the short version. Here's the long one: I've done the 25-mile round-trip commute to the same office regularly since 1981--hundreds of rides, if not thousands. For years, I rode in toe clips and what used to be called "touring" shoes, and I had a really good idea of my average time and speed, as well as how I felt coming back uphill, usually into the wind.
When clipless came along, I got some shoes and pedals and rode that way for awhile, did the mandatory falls before I learned to get out of them etc--but they didn't seem to make a difference in efficiency or speed, and the clipless pedals limited me to cycling shoes. I couldn't ride to lunch or out for coffee in my street clothes.
I've gone back and forth many times, trying Looks and SPDs on three different road bikes and two mountain bikes, and I just don't see a significant difference, certainly not enough to justify the cost of tossing usable shoes and decent-quality platform pedals and buying all new stuff. Right now I have toe clips on the Atlantis, which I ride to work, and clipless on the Rambouillet, which I use for longer rides, day trips and stuff. As far as I can tell, there's no difference.
The notion that you'll pull up on the pedals with clipless is probably bogus, by the way. There have been several studies done using strain gauges to see how people really pedal, and almost nobody actually pedals all the way around in a circle for more than a few seconds at a time. Certainly if you're comfortable with clipless and like the feel, they're fine, but don't expect a big improvement.