How it does that and how you can maximize the unit is taught in the course and you learn to tweak it to your particular needs as u dive the unit how to maximize your dive. Just like you do on a CCR. You will have no problem getting 2 or even 3 no decompression dives with the unit depending on the parameters that you decide to dive.
1) I don't disagree with you about "maximizing the unit". My point was, I've *yet* to see an Explorer diver who is following the computer (and not tricking it) get *more* dive time on a single dive than what I can get out of a single AL80 or HP100. Now if you want to drop down to 130ft for two minutes, and then do an 80 to 100 minute safety stop that is probably dive site specifc.
2) The parameter you're changing on the Explorer is the DCP. You're not manipulating the SP as you would an a CCR. You're proposing it's esentially the same thing, but it isn't and it's very important to understand the nuance here as it could get someone hurt. As a CCR diver I'm holding a SP, which means I can actually very accurately plan a dive. With the Explorer, I can't plan the dive using any common software, I have no idea how much inert gas uptake or O2 exposure I'm going to experience in actuality. In truth dive planning is nothing more than a fruitless exercise. People claim the Explorer will hold a minimum PO2 at or greater than an air dil equivalent. In my experience, this claim is absolutely false. If this were the case, you could simply use a backup computer set to air and then track NDL/deco with say a common dive computer. With the Explorer, I can't really back it up with a second computer because it uses a decaying PO2 model. You're never really on the SP, you're always breathing away from it. All the DCP does is determine how much gas you want to invest in staying close to the computer selected SP. You can't plan for a SP, you can't select the SP, you can use the known SP in advance to plan your dives. Your diving day is determined in large part by whatever the computer wants to do. This is probably excellent for the market the Explorer is targeted toward, but nothing like a real rebreather where control of the SP and knowledge of the PO2 is everything.
Because the handsets lack the ability to run in detached stand-alone OC mode, and considering the PO2 is not stable to a minimum air-dil equivalent this makes any subsequent OC dive after a rebreather failure a walk into the unknown. With a CCR, I can switch back and forth to OC all day long and know exactly where I'm at on the model. I don't find this as a fault of the Explorer, however the assertion you should always bring OC gear with you in case of a rebreather failure is a bit silly. Is the average recreational diver really going to know how to calculate deco for this situation? My suggestion would be that Hollis adds a parameter to the Explorer which absolutely never allows the PO2 to drop below the equivalent of air dil thereby overriding the DCP. If they did this you could dive again on OC, but you'd need a backup computer. Granted diving against an OC Air plan after an Explorer dive is going to come with a possibly unwarranted residual nitrogen time, but who knows? It all depends on the implementation, I suppose.
If I were king for a day, I'd add the necessary CPU power to the handset to make it essentially a detachable DG05. By doing this you get essentially double the value out of the computer, and you can use it to plan dives regardless of the health of the Explorer. Should the Explorer run out of resources? No problem. Select OC mode, grab your OC gear for the next dive, and go. Right now, you kinda have to just decide diving is a good idea and go for it using another computer. Probably a cost-cutting move to run a less powerful CPU, but a detachable computer capable of calculating OC dives would have benefit in the sales pitch.