Chaser, review the photo of the Perpignan A320 on page 50 of this thread. Note the lack of large floating debris to be picked from the surface. Review the Armenian Airbus crash off Sochi into the Black Sea from a very low altitude and relatively low speed (much less than cruise) during a go-around in weather. Note the difficulty finding and retrieving floating debris.
RWA
as far as any of us know, the signals ended either because the aeroplane had either dived straight down into the sea (at a descent rate of the order of 8,000 feet per minute) in that four-minute period,
Few or none of those who know would believe this flight dove straight down (all the way) into the sea.