you likely won't hear from them because you aren't an authorized service technician. I'm much more familiar with the Poseidon design, and believe the Oceanic/Hollis is a downstream design despite being servo actuated, so take this with a grain of salt.
The 500SE is a knockoff to the Poseidon Xstream, but more closely resembles the downstream design of the Oceanic Omega. It's a big strange, but that's beyond the scope of this. Point being, the IP of the first stage will directly control how easy it is to "Crack" the regulator when you first start to breathe. On upstream designs like the poseidon, the higher the IP, the harder the cracking pressure, on other regulators it is the opposite which is why when you have too high of an IP they will freeflow. These require an OPV built into the system either in the first stage, or on the hose, downstream designs have the "OPV" built into the mechanism.
The difference between 125 and 150psi is not a whole lot in the grand scheme of things, and for $15 you can buy an IP gauge and check to see what the sherwood is set to, you can get a better idea. Moral of the story is 125-150 psi to match with 140psi is close enough and you won't notice any difference in breathing effort. IF this is an upstream design, it will still work fine, you just have to put an OPV into one of the LP ports. I find no reference to this in any of the Hollis or Oceanic literature on the regulators, so you should be fine.