I've send Deepblue a few emails saying that I don't think they have created a safe computer and have expressed my concerns about how what they think are "safety factors" are actually incredibly dangerous to the point that I would not be able to use one as a primary computer in a teaching environment and because of that, despite being an ambassador, won't promote it yet. Thankfully it is all programming things that they can update whenever they want, but I'm trying desperately to get them to do it.
I basically said this
Read Shearwater Recreational Nitrox mode
write code that makes your computer do what it can: 3 options for gradient factors, 3 gas mixes with decompression, and NEVER locks you out, for any reason. Continuously tracking your tissue loading regardless of what's going on. Any computer that doesn't do that is dangerous to me because if you HAVE to descent again for some reason, the computer just shuts down and that's a deal breaker for me.
regarding VPM, the reason you have to pay for the upgrade is because Shearwater has to pay royalties for the VPM algorithm, so it is there to cover their fees. Super annoying, but I don't have any faith in that algorithm anyway.