Modelsim VCS IUS Comparison

They are three best mixed language simulators. VCS (Verilog Compiler Simulator), formerly from Chronologic but now owned by Synopsys, IUS (Cadence Incisive Unified Simulator) from Cadence, and ModelSim from Mentor Graphics. The answers to which is the best vary by project. Usually VCS and IUS are faster than Modelsim, and Modelsim uses more memory.

Does IUS include IDTS(Incisive Design Team Simulator) and IDS (Incisive Enterprise Simulator)?

Some user's answers for comparisons of Modelsim, VCS and IUS:

http://www.edaboard.com/ftopic225208.html

http://www.deepchip.com/items/snug03-06.html

http://groups.google.com/group/comp.arch.fpga/browse_thread/thread/96cad9548a7f92e6?pli=1