Before you go searching out a new derailleur, check the cable to make sure it isn't at fault. Just release the cable bolt and if the derailleur moves further inward, it's likely the cable. Sometimes you can increase spring tension sufficiently by slipping a piece of tubing over the spring ends. Also make sure the travel limit screws are properly set.

I don't know when SunTour switched the operation of their front derailleurs, but I can guess why. Even though their approach made more technical sense, it wasn't the normal operation and it was confusing people. Shimano's Rapid Rise rear derailleurs also used the spring to facilitate shifts onto larger cogs and they didn't catch on either. IIRC correctly both the SunTour Spirt and SunTour Compe V were the reverse action front derailleurs, though I don't know if they have sufficient travel for a triple.