It's really getting down into fine details... but that's sort of what this is all about... DCOs produce a sound/character that is 95% of that of VCOs... its just a matter of figuring out that last 5%.
On a side note, I had a breakthrough (related to this, but slightly different), that has totally changed my thinking about VCO synth emulation. I'm gonna do some more work on it... currently applying it to a bunch of my custom patches. I'll have some thoughts (and patches) to share soon 
I had a breakthrough today as well, I wonder if it's similar to yours.
For a few weeks now I've been researching options to warm up the Rev2's Curtis filter. I've considered (stereo) external devices like the Strymon Deco, Analog Heat, Boss SE70, Vermona Retroverb Lancet, and the EHX Mod Rex. Heck late tonight I even had a realization that I could possibly use my Line 6 HD500. The idea was to warm the Rev2 patches and use program changes to line up the FX with the Rev2 programs.
But that's not the breakthrough.
I realized that the root cause of the unpleasant character was not only the filter but also the oscillators. I listened very closely with headphones on to an INIT program, and heard artifacts. They're a bit like the crackling of fire, and it may be due to distortion in the signal. There was also a very slow undulating in pitch/amplitude, but none of the LFOs were assigned. I immediately thought of Creative Spiral and how he probably already noticed this and maybe even had a video with an oscilloscope or spectrum graph documenting these artifacts.
Anyhow, these realizations came as a breakthrough to me, and I started synthesizing a gentler, warmer, less-Curtis polysynth sound with interesting evolving motion using these techniques below. The goal was to sweeten up the oscillators and change the response of the filter and envelopes away from the standard Rev2 defaults.
- LPF ENV routed to its own Attack and Decay to change the ENV shapes
- ENV3 source to LPF ENV AMT. Envelope delay about one second, mushy attack, long decay, near zero sustain, enough release to avoid the "plop" sound.
- Very slow LFO and but near max AMT to OSC1 shape (assuming knob is fully counterclockwise). Ditto for OSC2 shape using a different LFO. Note that the audio artifacts are most noticeable on the default INIT saw. Sweeping the shape very slowly provides something like a smooth filter sweep and minimizes the spiky or brassy character
- OSC MIX at 3 o'clock or more, favoring OSC2. There is an unpleasant phasiness when both OSCs are heard equally.
- OSC2 set an octave lower, matching OSC1 Sub. Mixing these 2 is warmer, and these can be detuned more pleasantly. OSC1 itself is only very lightly heard, contributing harmonics an octave above.
Of course the other standard warming techniques apply as well -- pan spread, slight (random) LFO to cutoff, slow pitch LFO with ENV3 used to delay the onset of the vibrato, low ENV AMT and keytracking, very slight Audio Mod, FX distortion around 140-150 with minimum tone and max mix.
Long story short -- slow waveshaping, varying ENV AMT with ENV3 or LPF ENV, and OSC mix favoring only one of the OSCs. Like the story with the Andromeda OSCs distorting early, sometimes less is more.
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