Yes, they are superior because they are "at least +3", that means, they can hit almost any monster in SoA (exceptions: Great Mummies and Kangaxx need "+4"). For example, they can hit Iron and Adamantine Golems, Glabrezus, etc. Moreover, the bows have an unlimited supply of the phantom arrows so that you cannot run out of ammo while firing phantom arrows.
With the Tansheron Bow, Adamantine Golems are simple
Let them hang in a door, catch the bow and fire phantom arrows. Well, Adamantine Golems are highly resistant to weapons but they aren't immune, therefore, it will take a while until they fall but they fall in the end without getting any possibility to harm you. You will score 2 - 6 HP per hit.
An additional note. If you have the "bonus merchants" installed then you can buy the best phantom missiles firing weapon: the Sling of Everard. It fires phantom bullets considered a "+5" weapon. The sling costs bags of money but it is worth it. It is the best ranged weapon for your priest [img]smile.gif[/img]