Depending on the complexity of the Mechanical System and the size of the building too. Take with a grain of salt, but all of us, at one point, thought it was taking for ever. PM's and other engineers frustrations escalate when they cannot control someone else's time. So far, as a rule of thumb, at my prior employer's I've taken (per buidling) 80hrs on a ~20,000sf office building with one VAV system...up to 185hrs for a ~180,000sf 5-story barracks with a more complicated system/s. That was from beginning to submission to LEED not including documentation or filling out LEED forms. That said you can also break it down like this, if 20% is put into setting up your design to get equipment selections and design building performance, then it will take another 80% to complete the LEED Energy model...keeping in mind that without due dillegence to accurately model, the penalty will be having to anser many LEED reviewer request for more information, clarifications, and additional questions. So take it for what it is, and do it right to the best of your knowledge upfront.

In the event that you get (and you probably will) responses back from LEED, you get 25days to respond. That does not mean you go to the modeler and say you have 25days get-r-done. We've developed a good practice in our projects to set up a dialog with the PM. You have 25days, but meet on the 12th day and discuss if it's done and the modeler just needs to update the forms and supporting documents. If the modeling still needs work, then the PM should request an extension (of reasonable time 30d, 60d, 90d).

Now BobF is probably one of the best people to answer your question as far as if one can outperform the other when it comes to modeling, since I have not had the chance to learn eQuest. IMO Trace700 does it all (someway or another) and automates supporting documentation (don't forget that part since that could take up to another 40hrs to compile or write from scratch)..