Operating under Windows I run out of memory every day. A combination of file size, length/intensity of session and poor memory management seem to be the cause. Under MacOS all available memory can be grabbed in a matter of minutes.
On the Windows side with a rapidly increasing proportion of 64 bit machines, it seems logical to have a 64 bit version of the program.
On the MacOS side it is illogical to produce a 32 bit program which can only run on 64 bit capable machines.