It's not worse than the trip positive on the higher dr liches. That's the point here it is better on elite abbot and epic wk by up to 7 dmg per shot and only very slightly behind it on hard. 7 damage is a big difference and that doesn't even factor in the fort reduction.
Look the fact is triple positive against undead is ridiculously good. When they made the greater disruption changes it put this thing so far ahead of any other undead beater that it's not even funny. An impossible to loot +5 holy burst of disruption with a large guild slot doesn't even come close to compare. The best cannith crafting option same thing. They even made the new mournlode epic weapons for the challenges, stacked them with some pretty nice effects, and they are not even better with the exception of to hit mattering. And notice I have said nothing about a bow here this is true for any weapon type except handwraps and if there were triple pos handwraps even the mabar wraps would be well in 2nd place.
To say that this bow even in rare circumstances can outperform a triple positive bow is making a pretty good argument for the bow. If they made it any better with this base version they really couldn't add much at all to the epic one with out having an out of balance item. The epic version is probably going to beat out triple positive on any blunt dr skeletons as well as vampires too if silver arrows not used.