You’re all over this thread being wrong and confused.
Source: am a rocket engine designer.
It seems like the major win here is running oxygen rich on the oxygen side and fuel rich on the fuel side to reduce the chance of a leak destroying the whole vehicle.
Am I missing something?
You have higher pressure in the chamber with full-flow approach. Since the mass flow is the same, and Isp is higher, thanks to higher pressure, you're winning.
And you have higher pressure because you supply more power to pumps.
Reducing risks to destroy the vehicle due to leaks is, I agree, very secondary benefit. May be even tertiary - how about possibility to optimize turbine frequencies for both propellant flows without losses on gears?
The turbines in any kind of staged or full flow system run at a pressure higher than the chamber is at... I don't remember the numbers offhand but I want to say the SSME's preburners were at 8000ish psi, with a drop to 4000ish through the turbines, and finally to 3000 in the main combustion chamber. The SSME was only partially preburned, and so the flow through the turbine has to expand over a higher pressure ratio, but I still don't see a fundamental difference.
Higher Isp of the engine is achieved because the pressure in the chamber of full flow engine is higher, than chamber pressure of staged combustion engine.
The pressure in the chamber is higher because pumps produce higher pressure.
Pumps can produce higher pressure, because with full flow pumps have more power driving them than with staged combustion. Power here is roughly equal to volume flow (m^3 / s) multiplied by pressure drop (N / m^2). Full flow scheme gives you more volume flow, since all the propellant is used to turn turbines.
So even though all the propellant in both cases is burned in the chamber, Isp is higher with full flow scheme. Rocket engine maximizes momentum of the exhaust, not the energy, which is conserved.
You say the main benefit is just increased pressure?