Hi Justin,
with the "plaquette-singlet solid" picture of S. Todo, M. Matsumoto, C. Yasuda, and H. Takayama, Phys. Rev. B 64, 224412 2001. in mind I don't expect to see boundary S=1/2 excitations in S=1 two-leg ladders in contrast to the single chain. Indeed we obtained good agreement with the QMC result of Todo et al. in our paper PRB 74, 144426 (2006) using standard open boundary condition DMRG on a S=1 two-leg ladder. that might also remain true for wider ladders.
cheers,
andreas
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