I'm not with any of you all the way on this, but am with a surprising bunch of 'ya on various parts of it (and a motley crew it is!)
As Spectre pointed out, the Suuntos don't
say "go to 10 feet and sit" when you enter deco, but if you
do not understand decompression that's what you are
extremely likely to take both from the display
and their narrative in the manual! Indeed, the manual states (truthfully) that while above the floor you will decompress, but originally it will be very slow, and of course that you will decompress faster towards the ceiling. It leaves unsaid that going directly to the ceiling is unwise, and I can
definitely understand how someone could get that impression from the display AND the manual they supply.
IMHO, they're WAY remiss in the way its worded.
Second, the Vytec can handle 3 Nitrox mixes - so unless you're diving Trimix, it can indeed account for deco gasses....
Personally, I believe that you can learn MORE than you will in a class by making a study of decompression procedures, including getting a copy of Vplanner (nagware, and cheap to register - well worth it) and playing with various dive profiles. If you do this for any significant number of simulated dives (and simulating them is, of course, completely safe!) you'll begin to see a pattern if you have enough neurons working to actually DO this kind of diving. Given that understanding, IF the computer beeps "DECO" at you, the knowledge will be there to make a proper ascent, using the computer to VERIFY when you're "clear." If you DO understand how it works, the computer will effectively be your backup in executing this, because if you just did the profile on ascent, the computer would be clear before you go to the 10' stop it wants you to make (assuming we're talking "light" overstays here - no, I'm not talking about dives with an hour of mandatory stops!)
There is no "magic" about decompression. Yes, it can badly hurt or even kill you if you do it wrong, but
all dives are decompression dives. If you want to test this go ahead and stay to the NDL on a nice 100' dive and then do a polaris ascent, and let us know how much the chamber bill is, because you're VERY likely to end up with a chamber ride out of that.
NO, YOU SHOULD NOT DO THAT, FOR THE SARCASM IMPAIRED!
I intentionally dive with required decompression from time to time, and I have no "formal" training. I have made a study of how it works though, and I certainly don't do it without the required redundancy in my equipment to INSURE that I can meet the required schedule.
Decompression is an overhead that is just as "real" as a cave; if you cannot make your stops for any reason you are quite likely to end up hurt or worse.