Would be much better to make 100% success and change furniture's to 1 or 63% faster fuse ... So spending money would influence gaming much more than free to play. Maybe the "fountain of gems" would have some other additional buff's (5% faster fusion, 5% less tax, 5% speed for quest, 5% faster crafting....) for a better cashflow.
All known games provide better effect for player spending less money to game. I know, pay to win, but what you wanna win? The "Cold War" where skills of items maxbe dont work?