On Thursday, February 11, 2016 at 9:14:08 AM UTC-5, wrote:
Second is likely related to wing root separation issues which vary a lot from ship to ship. From my simple observation the gliders with larger well developed root fillets seem to be the ones that are not in the group described as benefiting from notable slipping.
One guys opinion.
UH

That would tend to correlate with early mentions of holding a slight slip in turns from George Moffat in regards to the Standard Cirrus and Nimbus II, both of which, IIRC, suffered from poor airflow around the wing roots while thermaling.

Chip Bearden