That sounds great. Here’s some random thoughts/feature requests for Guitar.
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Arpeggio picking. So many guitar styles feature it and it’s one of the more attractive features of the guitar (my instrument). From traditional finger picking styles to the sitar-like picking heard in Jazz fusion, to pop hits like those of Christopher Cross, it’s a ubiquitous element of popular guitar sounds. Some of the best hooks.
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Related guitar voicing. I often “walk inversions” when playing a progression on Guitar. Scaler already does this well, but applying it to guitar-possible vocings would make guitar parts sound more authentic. As references for “good chords,” I’d suggest Ted Greene’s Chord Chemistry – still one of the classic works on Guitar Chords and Sid Jacobs – great Jazz guitar chords and vocings, there’s so many others, too.
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Rootless voicings. It would be great if Scaler would take a common chord and then show us related Guitar Chords with tensions added and the Root or other chord tones omitted, as needed. This is very common on Guitar but can be tricky.
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Chord Synonyms. Ted Greene devotes some time to this, but it is a source of endless exploration and a good way to find new sounds and progressions. So, we enter a common chord, say “C7b9,” and Scaler would show us a set of chord synonyms for it (with chord tones/tensions added or omitted per taste).
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Open String voicing. Open strings in Guitar voicings provide a unique sound. If we add Alternate Tuning to that, the possible “good chords” expands tremendously. It would be great if Scaler could suggest chords that feature open strings. For example, C#-Minor 1st Inversion is great on Guitar in standard Tuning with the low E string. Sometimes the open string is a tension or suspension.
I could go on but don’t want to go into the TL/DR zone. I’m sure I’ll like whatever you do with Scaler re: Guitar stuff. I hope some of this is helpful and thanks for this great product which I’m not telling anyone about. 
Steve