Jabes.plays.RPG says:
I thought about adaptive, but if we're only playing for 4 levels then we're only looking at one more ability increase and I know I'm not spending it on Strength. So adaptive would be of no use. I got myself a Composite +2 bow. While we're on the subject, must an Undead Bane bow also have +1 magical enhancement? A +1 Undead Bane Composite +2 Longbow is gonna cost me 4,300gp. Would've gone with Holy but I can't afford it.
A couple things to remember:
1. You HAVE to maintain that 14 str with the bow or suffer a -2 to attack rolls. So if you get str drained (very possible when facing undead), you will suffer the penalties. This would not be an issue with an adaptive bow. This is actually the main benefit to the Adaptive Property, since stat drains are so painful otherwise.
2. A +1 Undead Bane Composite Bow (+2 str) would cost
8,300, not 4,300. It is a +2 equivalent weapon, and thus adds 8,000 to the cost.
3. Yes, you do have to have a +1 enchantment on the bow to even consider adding the undead bane property.