First, I'm grateful for this forum for gathering information. My tesla is currently in service getting the MCU2 upgrade. I plan on posting when it is complete.
The first thing I have learned is this 10% scam that tesla service provides for you to use your own main console screen. I would never have called it a scam if it wasnt a frequent theme with many owners from different states. If you look up tesla screen replacement, the cost can be anywhere from $1500 to $3000 dollars (likely with labor). When you purchase the MCU2 upgrade you are purchasing the MCU2 AND the expensive screen replacement.
In my interpretation, when you are offered a $250 discount, it seems like the service center is simply "buying your screen for $250". When they have that screen, they can charge the full amount to another owner and make a huge profit. Also, I have read that the older screens have tendency to have yellowing defects that require treatment. And you dont get the extended warranty you get with the the new screen, so if your screen fails, imagine the cost to replace or fix especially out of warranty.
When I dropped off my tesla yesterday to get the upgrade, I was told I would get a new screen. When they called today, they told me MCU2 was installed but they somehow had error and forgot to install the new screen and offered me the same discount. I refused the discount and told them to install my expensive that I paid for knowing they would have to open up the dashboard again. However they couldn't charge me the labor for it since it was their mistake.
So, it's not a discount to get $250 for an expensive Tesla touchscreen. Imagine how much an owner with a failed touchscreen that would pay you to get your screen for $250 and only have to pay labor to install it. In reality if your touchscreen is good, why not just pay $2500, keep your old screen installed and keep the new screen somewhere safe in case it fails?