From AUA Daily Scope (on line news magazine) and reported in the journal “Cancer” Jan. 2015

Early mild GI toxicity: IMRT 86.2% Proton Beam 95.7%
Late (chronic) moderate to severe GI toxicity: IMRT 10.8% Proton Beam 12.8%

Early mild Bladder toxicity: IMRT 71.2% Proton Beam 78.7%
Late (chronic) moderate to severe Bladder toxicity: IMRT 18.3% Proton Beam 12.8%

These numbers are worse than I previously believed. Radiation is NOT a free ride.
The most appropriate prostate cancer for radiation remains the big bulky tumor. Men under 75 years old who are recommended to have radiation for small tumors might ask if their doctor has an ownership interest in the radiation unit.