i have both. my pref is for the P1D. why?
3 o.p. levels v. 2 levels. almost never need the highest setting on the P1D for my uses, but at least it's there. if the EZ123A had three levels, like the Ra-Twisty, that would be a big improvement. However, i would want a LOW like on the Muyshondt Nautilus/Aeon instead of a LOW like on the P1D - this is my only "crab" about the P1D - LOW is NOT low enough, but then neither is the LOW on the EZ123. give me ~3lm or ~4lm, ~15lm, and a high at 100-130lm and i'd be a happy camper.
IMO, the P1D is easier to operate. very easy to switch b/t light levels on the P1D with one hand. on the EZ123, however, HIGH is just too far removed from LOW. i, at least, can't quickly tighten the head to go from LOW to HIGH (unless i use two hands which even a klutz like me should NOT have to do) - too many degrees of rotation separate the two levels, IMO. i can understand the reasons for this, but my pref would be to have them "closer" together (i.e., fewer degrees of rotation). i need to twist, reposition thumb and index finger, twist again, reposition, twist... you get the idea. i've even shaved/beveled the foam ring to make it easier to tighten, yet still keep the CR123A cell from rattling in the tube when the light is OFF.
for the way i like to use lights, the only plus of the EZ123 over the P1D is that LOW is activated first. i almost always want a low light o.p. first (which is one reason i don't like memory in a light, though that doesn't apply to either the EZ123 or the P1D).
now, this says a lot, if when one of my main LIKES is lacking in a light that i still prefer it over the competition.
i'm glad that i purchased the EZ123. please don't get me wrong, it's a fine light. if you choose it over the P1D, IMO, you HAVE NOT made a poor choice. enjoy whichever one you purchase (i'd say, 'save up your pennies and purchase both').