Review of RY4 Double Flavor-TFA:

I was looking to clone a local shops RY4 and I'll be damned if this isn't almost spot on solo.

I've had it at 5% and found it too subtle, honed in at 7% being perfect for me.  I like to add 3% caramel and 3% vienna cream and WOW.  Even better than my local shop.

Does take a couple weeks of steeping to really develop.