Further WSPR development?

On the LF reflector recently there's been discussion about how to make weak signal modes decode at even lower S/N ratios. Joe Taylor K1JT, who created WSPR, was approached by Stefan DK7FC, a very well known LF DXer, to see if WSPR could be further developed to achieve this.  One idea is a slower version of WSPR with a 4 or 8 minute time slot instead of the current 2 minute period. Theoretically it should be possible to get successful decodes with much weaker signals. Joe is currently busy with other work, but took kindly to Stefan's suggestion and said he would take a look later in the year.  With WSPR performance roughly equivalent to QRSS10, such a move would be welcomed by many of us trying to get reports on VLF, LF and MF with QRP.