We've chatted about this a little on the FB group, but my beef with this is two-fold:
1) I love the idea of true FlexFuel - the ability to change timing/fueling/boost by exact/true Ethanol content - this does not have the ability to change timing. In my opinion (multiple 1k whp+ E85 cars) timing is the much more important piece of the puzzle. GM and Ford can integrate the ethanol content sensor to gradually change between full pump gas and full e85 timing/fueling with the stock PCMs, Mopar can not.
2) Livernois and others have gotten a very decent FlexFuel implementation just using lambda sensors to 'backwards' calculate Ethanol percentage and thus change timing and fueling with no additional computers/sensors.
I'm very interested in tuners' experiences with this versus the stock PCM using the 'calculation' method, and versus GM/Ford true Flexfuel tuning with a content sensor and stock PCM.