I just installed Glacier Bay Elongated Dual Flush 1.1/1.6 GPF
Glacier Bay Elongated Dual Flush High Efficiency 1.1/1.6 GPF All-in-One Toilet - N2316 at The Home Depot
Without heavy filtration, I be afraid the Grey water would cause the filler parts needing to be replaced to often. Think it better to use rain water for the toilet and the Grey water for roses.
I have a lot of projects in motion now. Main focus is heat and insulation of the home. I have started rain barrels and later on when I build a storage tank in the basement for hot water. I think, I'll build a third one ( 500 gallon about 1*892.7 liters) for rain water and use it for toilet , cloths wash and garden.
Note on toilet: I like it.