We'd generally recommend a DPI of around 1,000 for day-to-day use. There's a bit of a DPI war between gaming mouse manufacturers trying to eke the biggest DPI out of their sensors, but ultimately these huge numbers are impractical. The 16,000 DPI you can get out of the Razer Pro Click seems impressive, but if you tried to use it in real life the tiniest nudge of your mouse would send the cursor flying across the screen. An adjustable DPI can be useful however, allowing you to change the DPI for different tasks, increasing it for gaming for example.