Its beneficial in certian cases. But I disagree that it helps tremendously with larger sites.
For example, if you run a wordpress site that gets a considerable amount of visitors load balancing is one option. However depending on the size of your webservers, you still have to cache the shit out of each www server to maintain speed. As such you will probably end up using something like memcached (so the cache files are the same for each www server.
Speaking from experiance with load balancing a wordpress blog that recieves massive traffic, I don't consider it to be an amazing solution. I actually found it easier to simply have the blog on one server and impliment loads of different caches.
I use nginx for everything and the load balencing it does is pretty good, but if you haven't used it before it might be a bit tricky. There are plenty of tuts around though.
That being said, perhaps an easier way to instantly speed up a site is to install an opcode cache, such as apc or xcache. If you are on a debian flavored distro, these are pretty easy to install. Compiling from source is not hard either with phpize.