I 2-ALL'd Pink Sweet's Extended mode. The first loop is slightly harder than regular PS. Still, I got the infinite lives trick triggered by the end of Stage 3, and cruised through the rest of the game.
Without the infinite lives trick, Extended mode is basically impossible. I recall reading a very skilled Japanese guy who could regularly 1CC the first loop with a good score without the infinite lives trick, but he said he couldn't get past stage 2-1 in Extended mode because the rank was too high and there was no way to lower it. This was after he played through the first loop with the lowest rank possible (suicides, no medals, no bombing, etc). He considered a 2-ALL of Extended mode completely impossible without the infinite lives trick.