I've got Party Level 251. Many of my Heroes are maxed at level 31. I've got 209/260 stars filled. I'm working on area XII.
The Amethyst drop rate is a serious road block to progressing. I've got over 1000 Topazes, 300 Emeralds, 150 Rubies, but I rarely get Amethysts to upgrade my gear. Plus at 25% success rate, it's slow going to get my gear upgraded so that I can progress further.
I'd like to suggest that you give us the ability to trade up or trade gems down. Like 10 Topazes combine to an Amethyst and 1 Emerald breaks down to 10 Amethysts.