After having both, I'd rather monitor rail pressure and have a simple light for the AirDog (or FASS in my case). I have a rail pressure guage, mechanical guage under hood, and a low pressure light on the FASS... I don't think I have looked at the guage under hood in months (and a light will catch your eye faster).
And you can still catch a plugging filter with a low pressure light, it will start flickering at WOT well before the filter actually plugs.
On the 3rd gens, your good as long as you have pressure to the CP3, its not as critical as the 2nd gen VP44s...