I have had Don Sachs amp and preamp since they were first offered and I covet them. I have since upgraded to his new preamp. I haven't heard the pricey Raven gear, but have a hunch that Clayton has heard Don's Vallahala integrated amp, and it strikes me as veritable bargain for its level of performance. Or so Don's customers tell him. I guess to the OP's question, I have no comparative information about the Vahalla vs. the Raven, so my post might be of no value, other than to affirm the excellence of Don's gear.
Don has been in the audio world for decades and it is informative to see how his gear, which is carefully constructed for each buyer, but not in large quantities, is compared to several other large audio manufacturers as a standard of excellence in tube audio amplification. There is a reason for this, as geerock and others have noted. Cheers.