I want to use REG0 to supply 1.8v to external 4.7k pull-ups including when the system is off. Looking at the product specification REG0 can supply 1mA while in system off. If one pulled-up line goes low the resistor would consume 0.38mA. I will have six lines and all will be capable of waking up the system.
My concern is that if 3 or more lines are pulled low before the system wakes up then the resistors will consume too much current. I'd hate to implement a regulator just to power some pull-ups. Do you think the system can wake fast enough to handle the current if 3 or more lines are activated simultaneously or should I implement an external power solution?
1.14 mA is probably fine, there is generally some margin in the spec. However the regulator is really not designed for this, and this load it in no way verified or approved by Nordic. It is up to you how much risk you feel is acceptable to avoid the extra circuitry.
Thanks for the help! I'll add the regulator just to be on the safe side.