Yup, most reviews report only marginal performance differences between high- and low-latency RAM. A few percents only.
Think of memory timings more like headroom for overclocking. The advantage of low-latency RAM is that you can can loosen the timings to achieve higher FSB and RAM speeds. Essentially you trade latency for speed.
If you're not overclocking, don't bother getting low-latency RAM. Save the money and buy more RAM, better videocard, etc. It's a wiser move in my opinion.