You've got the uModII already? Well, don't let it go! I've thought for a while that that was a superior piece of gear, especially due to the separate "SUM" and "DIFF" functions. Most ring mods don't let you go there, and if you can find a quadrature VCO to pair with it, you can get fairly close in behavior to a Bode Frequency Shifter. Not spot-on, but pretty close.