In regards to the poll itself, yes, I would say that to shrink the show from an hour to a half-hour is perhaps the biggest and most radical change yet. From day 1, SST was always an experimental show, and adding EW and changing from a commercial/magazine to a block format was all part of the on-going experiment since it turned out kids were losing interest in the show during the last fifteen minutes, and that kids like predictability. The episode count going down isn't unusual for any show either; back in the early days of television, a weekly series used to have upwards of like 40 episodes a season, by the 60s that number dropped to like 32, by the 70s it dropped to 24, by the 90s 13, by the 2000s 10, and now in many cases shows can have as little as 5 or 6 episodes a season.
But yeah, cutting it down from an hour to a half-hour is quite the major change: in spite of a shift from magazine to block, the show still has a consistent tone to it throughout, because it was still an hour show; cutting it in half and losing half the content feels like a less natural change.