I do think if I owned either I would be somewhat longing for filter cutoff / resonance though.
I don't own an STVC, so I don't know for sure, but there's apparently a mod matrix of 5 slots, where the solo section filter frequency is a destination, resonance another... so you could use the mod wheel or an external midi CC controller for that. Far from the same as having those knobs on the hardware though. Some interesting mod sources, like the LFOs for the chorus and animate FX. But not the AD/R envelopes as far as I could tell, which seems odd.
Having owned the Streichfett for some years, I was highly skeptical at first but I've come to really like it. I, too, feared that I'd miss a few knobs such as cutoff... I mostly would've liked the second knob on the FX section, as on the STVC. But then again, the FX aren't the best anyhow, as on Rev2, so to me they more serve the purpose of quite immediate initial sound design tools, where one replaces the FX later on externally for recording. The immediacy and "lack" of controls is actually what I've come to like about it, as odd as that sounds to me. Despite this, it can still do so much more than the vintage string machines. I always was a fan of that vintage sound, but the old relics were always too limited for me, so I mostly just sampled them into my Ensoniqs for further sculpting.
I think the Streichfett nailed it. It's not like an emulation of an old SM, and doesn't really sound like one, a bit digital sounding maybe, but a few outboard FX help with that. And you'd probably want to use FX with the vintage SMs anyhow, so no big deal. The STVC is indeed tempting, but I like the small form of the Streichfett, as I have to be quite economic with space...