I would suggest that you might want to try the Agent to Agent part of the site for a question like this one. I'd also suggest doing some research on the realtor.org site regarding surveys that NAR has done with home buyers. Perhaps there is local research in your area also.
The Calif. Ass'n of Realtors has annual buyer and seller surveys and one thing has not changed over the past few years - the buyer that purchases the home is represented by a Realtor about 90% of the time. Website like Trulia are all well and good, but your ability to reach the Realtors that have the buyers under contract is the best way to sell a home for top dollar.
I agree with Steve....there is no magic bullet. I use 4 different sites for the Siouxland area as well as my own personal site, will email customers to notify of listings, will email agents as a reminder about my listings.....I make sure my listings don't go "stale" and keep reminding folks that it is there and the benefits of owning that particular home!
I think it's a great site but as with anything it's how you use it and what else you do. There are many avenues to getting your property on the web and I personally use 6 different site including a personal site and remax.com. It's a matter of saturation rather than 1 magic bullet IMHO.