Easy answer.  The other software is Drake, which you also buy for $345 for up to 15 returns and then just $23/return thereafter.  I have used Drake when helping a colleague.  ProSeries is a better software overall, easier to navigate and more user-friendly, so it would be a step backwards to switch to Drake for all returns.  However, it makes all the sense in the world, considering the insanely low price of Drake, to put all NH business clients into Drake for the huge convenience of e-filing PLUS the fact Drake has the loss-carryforward form.