I have been playing with MotoCalc for some time now trying to piece together a good power system for my SIG Midstar 40. Can anyone vouch for ECalc? I am hesitant to purchase it, but would like to hear from anyone that has had experience.

How do the two programs compare?

I have used both. I had electricalc years before trying the free download of Motocalc. I think they are about equal in value. I know e-calc better so prefer it, but Motocalc is fine. Motocalc makes suggestions on which motor , prop, cell etc. to use ,where e-calc gives you just the raw data. Either is a very valuble tool. Either gives you ballpark values but show effects of various changes acurately