I am a hobby musician who likes to play various instruments. I bought the Strymon Deco v2 alongside a digital synthesizer. At the time, the decision was based on a plethora of positive online reviews, which overwhelmingly state that this pedal: 1) Gives a warm and thickened tone, and 2) Is compatible with line-level signals outputted by synths.
When I connect the pedal to the synth, this pedal delivers exactly what I had hoped for. In my hands, the left side (tape saturation) behaves like a 'Warm Saturator' between roughly 0-50%, and then between 50-100% a more noticeable compression/distortion is introduced. The volume knob is very convenient, and the tone knob is subtle but useful.
The right side (doubletracker) has a deeper functionality then I first expected. I use it for four different time-based effects, depending on the position of the 'Lag Time' knob. I would estimate that set between 0-30% it is a flange, between 30-60% a chorus, between 60-70% a slapback, then between 70-100% a delay. That delay is either a single echo (sum mode) or double echo (bounce mode). The blend knob functions nicely, and the wobble seems to introduce detune in the form of combined wow+flutter.
I was very positively surprised when I later used this pedal across various other instruments. One useful feature is the 'headroom adjustment' secondary function, which changes the amount of headroom between line-level versus instrument-level. This makes the pedal versatile across instruments.
For bass guitar, I really like using this pedal. I generally set 'Tape Saturation' to medium and 'Tone' to low. I leave the doubletracker off. Somehow, this makes the bass more noticeable in the mix, without needing extra volume. For example, when holding sustained notes on the bass, they seem to ring-out in a pleasant way, with less muddiness. This is useful in a band setting.
On electric guitar, the usefulness of the tape saturation side is probably a matter of taste (I would vaguely describe it as a warm saturation which fits for many genres, but if you want heavy distortion you will be disappointed). The doubletracker side seems to fit nicely to electric guitar, in particular the slapback as 'tone thickener'.
A note on the flange: I really like the flange delivered by this pedal! This is partly because the blend and wobble knobs give good adjustability of the flange intensity. But mainly, this is because the architecture of the doubletracker side enables a 'through-zero' flange effect. I might be wrong here, but as I understand, this pedal does not have a 'wet/dry' blend. Instead, it blends together two processed channels. Therefore, it is possible to set the time offset of the lag deck 'ahead' of the reference deck (ie: negative time delay). Then the user can sweep the lag time knob, such that the lag deck goes ahead or behind the reference deck, giving a through-zero effect. (Note: I am not a professional and I might be wrong about this).
The pedal can also be used as a stereo splitter (mono-in, stereo-out) via a secondary function. This works nicely, and there is some flexibility with the outputted stereo signal (eg: pan, detune on R channel, ping-pong double repeat delay).
