I've been playing with ArcGIS SDK. It looks very interesting, however I stumbled on a strange and for now unsolvable crash that sometimes happen in standalone mode.
Are there any B4X developers working with ArcGIS?
Well, "working" and "ArcGIS" is stretching it. I do, however, have QGIS installed and have used it a couple of times. Probably not relevant to you, but I thought it might be worth mentioning.