I did some testing of the new 3.21 worlds firmware today, the results are mixed.
The following was observed the first time I ran these tests, I subsequently tested again with standard 3.21 firmware but was unable (so far) to duplicate the results. In other words, the standard firmware was able to establish a link every time I power cycle the cortex. No idea what to make of this, perhaps something to do with WiFi channel selection or interference, anyway, this is what what I fould the first time around.
Looking more closely at the failed link condition, it does appear that the user code does try and start as the LED in the digital port turns on, however, something then goes wrong.
The test condition used a cortex (hardware rev A3) running a small EasyC program tested first with the new 3.21_worlds firmware and then with the standard 3.21 firmware that is included with the current releases of EasyC (188.8.131.52) and ROBOTC (3.08). A joystick using 3.21 firmware was linked to the cortex with a competition switch connected set to driver control, power from the cortex was then removed and reapplied, the time taken to link back to the joystick was measured. This was supposed to simulate a reset to the cortex (for example, motors stall causing brown out or battery connector was loose). For the purpose of this test there was no backup battery.
The standard firmware links approximately twice as fast as the new firmware, however, 50% of the time it failed to re-establish a link giving a single green VEXnet LED.
The worlds firmware always managed to re-establish a link but this takes on average 19 seconds after reapplication of power.
A video showing a comparison between standard and worlds firmware when a link is successfully achieved is posted here. (click on image to play)
A video showing a comparison between standard and worlds firmware when the standard firmware fails to achieve a link is posted here. (click on image to play)
So my conclusion is that the new worlds firmware (in my environment) is slower to re-establish a VEXnet link after a power loss but is more reliable when compared to the standard firmware.