I have one of their pumps from when i did a remote mount turbo on my V6 F150. They specifically say not for use as a fuel pump. I had their "premium" version too.
Could the disclaimer be because 1) the one which makes no sense to me- it can't handle diesel or not flam-proof for gasoline, 2) my biggest suspicion why- a lot of people don't know what a pressure regulator is and they don't want the liability for wrecking IP's or flooding engines/ blowing out carbs etc?
I wonder what other reasons there could be?
Their site says this:
Alternative applications
The pump can be used as a transmission fluid pump, to pump system coolant, and as a
pressure pump for water/alcohol injection.
It can handle diesel fuel as well. All the same
conditions/suggestions above still apply.
for this pump:
http://turbowerx.com/Scavenge_Pumps/Base-Model_Pump_Manual/files/Base-Model Pump_Manual.pdf
Since it's used specifically for oil, and can take diesel per their instruction, a WMO set up seems perfect to me. The only dilemma I see is, it only primes to 5 feet (suction side), it is designed as a pusher so relocating to the rail may be necessary.
Maybe the one you have/installed was/is different?
$150-$200 saving will buy some other good stuff too, like the regulator and line.