With the LEP II Higgs search approaching exclusion limits on low values of tan β ~ 2 it becomes increasingly important to investigate physical quantities sensitive to large masses of a pseudoscalar Higgs mass. This regime is difficult and over a large range of tan β impossible to cover at the LHC proton proton collider. In this paper we focus on the achievable statistical precision of the Higgs decay into two photons at a future γγ collider (PLC) in the MSSM mass range below 130 GeV. The MSSM and SM predictions for Γ(H → γγ) can differ by up to 10% even in the decoupling limit of large m_A. We summarize recent progress in both the theoretical understanding of the background process γγ → qq̅, q = {b,c}, and in the expected detector performance allow for a high accuracy of the lightest MSSM or SM Higgs boson decay into a bb̅ pair. We find that for optimized but still realistic detector and accelerator assumptions, statistically a 1.4% accuracy is feasible after about four years of collecting data for a Higgs boson mass which excludes tan β < 2.