Neither of these scenarios is a coin toss. For it to be a coin toss, the result needs to be randomly chosen. i.e. after the room stops spinning, either the person in Chamber A or the person in Chamber B drops dead, with the survivor entering heaven. As it stands with how you presented them, there is no coin toss, as the outcome is fixed; in Scenario 1, the person in Champer A always enters heaven, and the person in Chamber B always dies, while in Scenario 2 the person in Chamber A always dies while the person in Chamber B always enters heaven.
So yeah, the choice in both these cases is blatantly obvious. I would always enter the chamber in Scenario 1 as I have nothing to lose and everything to gain, and I would never enter the chamber in Scenario 2 as I have nothing to gain and everything to lose. The second school of thought is fundamentally flawed because "same" and "identical" do not mean the same thing. Even if in Scenario 2 an identical person as me is entering heaven, it is still not me, so the two scenarios do not in any way have the same outcome.
(Warning, soapbox material below)
Spoiler below!
The common confusion around the issue of the coin flip regarding SOMA is two-fold. First, people assume that there is some form of randomness involved when Simon gets scanned. They think that when a copy is made, one of the Simons is the original and one is new, with no way to determine which is which. Those people, however, fail to grasp the meaning of the word "copy". When a Simon is scanned, that is all that happens - he is scanned. There is no process that rips his consciousness from his body, jumbles it up in a randomizer, then assigns it arbitrarily to either the old Simon body or the new Simon body. It is merely copied, and the copy is placed in a new vessel. It is exactly like if you put a document on a photocopier and hit print - the original stays in the scanning receptacle while a copy is produced and spat out the other side.
The second claim is that the coin flip is real because to the Simons it "feels" real. This claim is often accompanied with a hypothetical scenario in which a man in a room is copied and the copy is placed in a different but identical room, and while there is an original and a copy it is impossible to tell which is which. This is an accurate representation of a perceived coin toss scenario, but it is not what happens in the game. The original is in one distinct place, and the copy appears in another distinct place, and it is immediately obvious which is which, including to the Simons themselves. The only reason that Simon-3 at Omicron considered himself the "real" Simon is because of his ineptitude in grasping the concept. Catherine tried to explain it to him several times, but he just couldn't get it.