IF totally HEAT SOAKED, that Idle pressure is ok... If the Idiot light comes on it is a problem. Most of these engines are roller bearing and don't require a lot of pressure. Normal is like your bikes are showing.
Personally, I Don't leave my bike Idle very long. I TOO don't like to see the pressure drop down to 10 OR Lower on my gauge.
IF really TOO low, the lifters will KLANK before you run oil dry enough to do damage to the motor... Idiot light "On" and KLANK from the Dry lifters = PROBLEMS.
I use a 20/50 oil from Redline, so I know I have good lube.
Are you guys running Oil Coolers? That does make a difference on keeping the oil Cool...Stop and go will get Hot no matter cooler or not.
Are the RPM's UP to about 1100 /1200? that IS needed here at Idle...
IF at "0" the lifter WILL KLANK...... LOUDLY
signed....BUBBIE