Actually, A2B provides the 1/2 credit bonus to its memebers on free upgrades to BC.
Half-credit A+ Rewards bonus for complimentary upgrades (full coach passengers in Y or B class only). A+ Rewards is our unique frequent flier program that can offer customers a coach flight in as few as three roundtrips in Business Class.
http://www.a2bcorporate.com/a2b_corporate_program.aspx