This experiment was originally designed to compare the skywave performance of these two antennas. However poor radio conditions meant that insufficient data was gathered to allow that. Fortunately two receiving stations within 20km of the transmitting site allowed a comparison of groundwave performance.
WSPRlite simultaneous S/N difference data from M0REP Download data here. Bearing from test site to M0REP 315 degrees.
WSPRlite simultaneous S/N difference data from G3CWI. Download data here. Bearing from test site to G3CWI 180 degrees.
The location of the receiving stations was not optimal as G3CWI was in the null of the STL.
Using the median data from M0REP suggests that the GP was 9.5 dB up on the STL on 20 metres (169 simultaneos readings).