I settled on the Inward Connections Mix690, at least for the time being. It sounded best to me in the Vintage King "Hear the Gear" samples, and definitely beats the D2BLT and Folcrom I used to own. The Tonelux OTB16 and Rascal Tonebuss are the two remaining contenders that I'd like to shoot out at my place someday. There's a thread somewhere on GS where people posted summed mixes using various mixer/converter combos. Here it is:
ANALOG SUMMING COMPARISON (this time its different)