I would like to suggest an optional alert sound in case of no gps signal.
During the last year I have regularly had a situation in which I thought my "prestations" :-) where being recorded just to find out afterward that there had been no gps signal or it was lost during my training.
I would like the possibility to have a spoken "no gps" or "no (valid) gps signal" message every speech interval.
To be honest, when I loose the gps signal during a training I would prefer a "dive alert" type of warning.