I had my update performed as soon as it was made available, many months and miles ago. The only difference I have observed (using an FIS+) is less boost during the "blowtorch" warm-up cycle. My mileage and regen intervals were not affected (documented) and I don't "feel" any difference in power (subjective).
I take the MFD mileage/range/consumption metrics with a grain of salt; calculating the mileage at each fill up is the true measure. Bear in mind that the re-flash may have reset the parameter/MFD registers, which may account for the abnormal fluctuations you're observing.
This reset might be what I'm experiencing. Still weird to see 710 miles per tank upon filling instead of 550.
In terms of the power, I felt that 1st gear of the DSG was just a "phantom" gear that didn't do much until 2nd gear is hit. It felt like the drive-train was "riding the clutch" at all times while in 1st. Then I'd get a rush of power as the clutch finally lets go in 2nd. Many times I'd chirp the tired in both 1st and 2nd because of these rushes of power. Now it's greatly muted on the shift from 1st to 2nd.
I'd only get to experience true 1st gear if I manually shifted the DSG, and even then it was:
1. very limited due to the gear ratio
2. even in manual mode, the DSG was always hesitant to actually give me first. It would ride the clutch if I was in any kind of motion and I'd literally have to stop to get 1st or I'd get first right before it needed to shift to 2nd. Is this normal operation for 1st gear in a DSG?
After the update, in addition to the drop in power between 1st and 2nd, I've noticed the DSG no longer rides 1st gear to warm the car up when cold but hold it in 2nd longer now. Now the DSG wants to get out of 1st as quickly as possible.
