It's even better than that. The upgrade only replaces the part of the fan housing that you see from inside the cabin (as well as the small arm that lifts the dome).
The fan, the motor, the dome, and most importantly, the part of the housing you see from outside the teardrop are not changed. That means that you do not do anything to the seal between the fan housing and the roof of the teardrop.
Basically you work from inside the cabin, first unscrewing the plastic housing that holds the screen and the controls. A few wires need to be disconnected to completely remove it. When it comes down you still have the rest of fan, and its seal to the roof, still in place. Then you remove the old lift arm and replace it with the new one. The new lift arm needs to engage the new motor so it can raise and lower the dome. Then the new housing is wired back to the fan and connected to the new lift arm (the new housing has a lift motor) and finally it is pushed up back into place and screwed back in.
The stock fan has four controls: the knob to raise/lower the dome, the in-off-out rocker switch, a three-speed fan-speed switch, and a temperature control.
The upgrade has three controls: the knob to raise/lower the dome (which has now become a push-auto, pull-manual knob), the in-off-out rocker switch and a new rocker switch to turn the moisture sensor on and off.
The remote is roughly the size of a deck of playing cards, just a little longer. It has an auto/manual/off switch, a couple of up-down arrows and some red LED lights. Press the switch once and you are in auto mode. Then the up-down arrows select the temperature, shown by the lights in thirteen steps. Press the switch again and you are in manual mode where the arrow buttons select the speed, again in thirteen steps.
What we wanted out of this was the fan speeds at the lower end of the speed scale. Move some air and be quiet about it...
As I said, we have only been out with the upgraded fan three times so we don't have a lot of experience with it but we are very happy with it so far. We have mostly used the manual fan speeds but have tested the other features briefly. We seem to like the third and fourth fan speeds from the slower end of the scale while we are sleeping.
Hope this helps to give you an idea what actually gets upgraded and what it looks like when you are done.