There's a new complex VCO on the market, just hit in the last month: VOID Modular's Gravitational Waves. It has everything you'd expect out of the DPO, etc, plus an onboard ring mod. The two big differences here are the size and price: 18 hp, $250. You could fit one of these into a DPO's space and only need to clear 8 more hp to put in a second...and two together cost less than a single DPO. Sounds like a win to me!
And yes, you do need three VCOs for maximal possibilities for sound design. Instead of the Rubicon, though...my take would be two of the above, plus a Doepfer A-110-6. That way, you also get TZFM capability along with a pair of West Coast-ish VCOs with a minimal footprint and minimal $$ outlay.