Musocity,
Most of these Giglads, JJAzzlabs and 3-4 others are very amateurish (I have done extensive homework on the subject). There are only two that I know are done more or less right: vArranger and Yamaha Mobile sequencer (iOS only) but even they have not been updated in years.
There is a new kid on the block, who is pushing pretty aggressively: Sofeh Sunrise. Very good start. The problem is none of these are in form of VST's. Syncing is possible by virtual midi and tying MIDI clock to be driven BIAB->Arranger. The issue is, it's not very stable and you get all kinds of anomalies.

Essentially what I proposed is an "updated" MIDI style maker / assembler from older styles. Non-modal, with direct preview from the chord sheet.