Shearwater said that the new firmware will store the tissue data in a new location and that the data won't be lost during battery swap, even if the super capacitor has failed. They also said that there would be no functionality loss. I guess that if that did work, you could make future Petrel's without the SC, no?
I run the Petrel 2. I'm thinking the super capacitor needs to be in there for clock and timing to keep them running and not make you reset them every time the battery is out. The rest of the functions are record data that can be written to memory and stay that way until you change it, I'm guessing.
To answer the compass question:
Yes, I like the compass feature but it has some disadvantages such as use of it takes up screen space and some data is out of view or shifted.
Also, if you carry a dedicated compass you see the entire compass face and sides. For good navigators, looking at any side of the compass gives you an indication of what direction you are facing, regardless of alignment. With the electronic compass, you only see a partial slice of the compass and in two dimensions.
To be honest, I used compasses more now than ever because I have it and the prior dedicated compass I considered clutter I didn't need.
One advantage is the compass is tilt compensated. Even if you tilt the unit 90 vertical(or down), the compass still works correctly.
The old physical compass needed gentle shaking to make sure it wasn't jammed or stuck and I had to hold it level all the time.
Also, you can calibrate it whenever you change your batteries or have extra magnetic fields around you (the batteries have a slight magnetic field). Calibration takes a minute and you can do it anytime by rotating the unit in several axis in "cal mode".
I used to love magnetic clips and cords and now I got rid of all of them. Speaking of...does anyone know where to by dozens of feet of spring coiled plastic cordage (looks like old telephone speaker and microphone coil) to make your own spring back cords for tools so we don't drop/lose them.