The biggest functional change was adding the new Output PWM control. Although the PID algorithm didn't change, this fundamentally changed how the PID algorithm is applied to your system. A more detailed explanation on the new output control features can be found on the
PID Implementation page. The update keeps with the BCS mantra of making EVERYTHING programmable and user accessible. This also allows 2 new parameters, Min Pulse and Max Pulse, that give further control. You can use the Max Pulse pulse to effectively limit the wattage of an element. For example, if you have a 5500 watt element, but want to be able to limit the heat for fear of scorching, you can dial down the Max Pulse, which is directly related to the wattage.. Set the max to 50% to effectively limit it to 2750.
The other new feature is the Alternate PID. Previously, any setting that was updated on the System Settings page was considered static. These included temp probe associations, PID tuning coefficients, and other PID/output controls. Alternate PID lets you swap these controls with other outputs in your state machine programming.
Overall, the new methods give much tighter control of your system, so I recommend upgrading. Just the new gauges are enough to upgrade. But, as with all firmware upgrades, you have to look at the new features and decide if its worth the hassle. All firmware updates to this point have been to add new features (not to fix bugs, as you can see by the Errata listings of each firmware revision). So previous firmware revisions are still solid.
Another reason to upgrade to 2.0 is that config files with v1.x aren't compatible with v2.x. This is because we had to add more parameters (and more space for future additions) to the config files to account for the expansion port additions. But I don't foresee changing this again, so config files saved with v2.0 should be compatible with all future firmware updates.
