Broadly, backslang worked but we had a very stressful time in the initial setup as we couldn't get a GPS fix in the location where the terminal was set up.
In order to maintain database consistency, all backslang nodes need a consistently accurate time, at least within human scale ie. 100ms or so. If one node has good time then the time sync feature of m2mMesh ensures that all other nodes should have a time sync on this scale.
Testing had show that the GPS module in use on the terminal could get a solid time and location fix indoors slowly when cold started but quickly once warm. However the location for the terminal was a building with a metal roof and this completely blocked the GPS cold start.
The practical solution was to place the terminal outside the building on a long lead, but this was disappointing from a usability point of view and we'll be making a V1.1 of the terminal with a hardware real-time-clock.