  We compute the predictions for the power spectrum of scalar perturbations
from a recent new proposal for the effective Hamiltonian of loop quantum
cosmology. The model provides an attractive picture of the early cosmos, in
which our classical Friedmann-Lema\^itre-Robertson-Walker universe emerges from
a quantum phase where the spacetime curvature remains constant and of Planckian
size. We compare the predictions for the cosmic microwave background with
previous results obtained within loop quantum cosmology, and discuss the
differences and similarities. The analysis provides an example of the way
differences between quantization schemes can be translated to physical
observables.
