MACE4 is an entirely different program from MACE-2.0 which is distributed with Otter-3, and the input languages are different. MACE-2.0 is usually better for problems with many multiliteral clauses, and MACE4 is usually better for equational problems.
An early version of MACE4 was entered (under the name ICGNS) in the first-order satisfiability division of the 2002 CASC theorem proving competition. Here is the abstract that accompanied the entry, and here are the results of the competition.