I have rebooted the Azbox by both methods, and if everything is OK with the .DAT files, then there is no problem, and the default sat list won't come back. However if you have corrupted data, the Azbox seems to detect that, and it will load in the default sat list, or actually, it seems to append the default list to your already corrupted list. I have no idea of what triggers the Azbox to do this. I have also rebooted by sending a reboot command via telnet (so that I didn't have to get up out of my recliner). The one and only time I used THAT method, it seemed to do some other strange things, so I haven't done that since, even though I'm 99% sure that it's no different from pushing the button in the front.
I have usually used the switch in the back, just because it is quicker than holding the button in for 5 seconds, however I think that for most Linux systems, it is safer to do a controlled reboot, because sometimes data isn't always written to disk properly until you un-mount the partitions, and you run the risk of corrupting data when just turning off the switch. However I think that Azbox seems to have taken measures to prevent such problems, so I usually just switch it off and on.
I have been intending to replace that default DVBS.dat file with my own shortened list, so that it would just bring in my list instead of the long list, however I've decided to just wait until it happens again, and THEN replace that file with a valid file. That way, I can put in the most up to date DVBS.dat file that I have archived. I have collected a variety of the 3 .dat files, so that hopefully I won't have to go back too far the next time things get corrupted. Also, since it seems to just add that file to the existing file, I'm almost thinking that it would be better to create a DVBS.dat file that only has a couple sats in it, that way you won't get so many duplicates. Actually, the duplicates are interesting, because it doesn't seem to duplicate sat names that I've left unchanged, but if I've changed the names of any sats, it seems to add the default sat name at that longitude..... I think.
I still am not sure whether the default sat list is changed each time you upgrade to a new firmware version, or if it is not part of the firmware, but instead part of a non-volatile memory that survives the firmware upgrade, and even the application area format. When I first got my Azbox, it seemed to have a corrupted list, and no matter what I did, I couldn't delete the sat at 1 W, and it would do all sorts of strange things when I tried, but I finally got that out using the .xml method with the AzboxEdit program, and that kept the box fairly stable until I tried playing with the diseqC-1.2 settings, at which point the Azbox reloaded the default list on me again. But I used FTP to put an older set of .dat files in there, and the Azbox accepted them, and I've gone through 3 or 4 reboots since by both methods, without it bringing the long list back in.
Anyway, what I should have said in one sentence instead of a short story, is that if the Azbox is bringing that long sat list back in, then it indicates that the existing sat list must be corrupted in some way.