I think it would help if he understood how these trading systems work in the first place. You can't even compare writing correct code with monitoring the profitability of the system. It's like comparing football with driving.

Well, that's all the better in that case. You've got two radically different computer programs, and you only blow up if both of them go wrong. I'd feel much safer with that scheme than a scheme where the computer programs are similar because then they might both share the same flaw.