Hhmmm, haven't heard this.
What reports have we concerning this being bad for the V7 850?
General observation as there are no reports as yet. The V7 850 is a new model. However normal engineering theory applies:
Freer breathing exhaust (no cat) made more freer breathing (remove db killer) makes an already lean (euro 5) running engine even more lean.
With other bikes / Guzzis this could be corrected with software of choice - Triumph for example - Tuneecu, older Guzzi - GuzziDiag, and loading new map / editing existing map.