i think you should probably prepare for something similar (but maybe try to rack up the intensity). these exams are personal in that your strength might be my weakness but I can tell you that for me the CPA exam was ranked by difficulty this way
AUD
BEC
REG/FAR
i studied a month for each exam (but no job so could dedicate about 3-4 hours everyday).
Personally, i found the GMAT a lot harder to be successful at (and my success is debatable - i'm retaking). with the CPA, since i have great short term memory, it was easy to answer a whole bunch of questions, read answers and figure out patterns and wrong answers.. it's a little harder to do that with the GMAT - and the timing factor also makes your mindset really important which did not come to play for me with the CPA (finished audit with 1.5hrs left and i took a lunch break).
So i'd say take a diagnostic test and that should help assess where you are.