You can find polar data from the Litespeed RS 4 here and for the Litesport 4 here. I took that data and "created" polars going through the two points on each curve assuming a total weight of 110 kg. I used Peter Gasparovic's interactive polar tool found here. Peter's program is a stand-alone JAVA application. I assumed fourteen square meters of sail area.

Here's the polar I get for the Litesport 4:

Here's the one for the Litespeed 4:

I then took Frillysoft's polar calculator to get the coefficients of the polar equations so that I could put the two polars together on the same graph. I had to eyeball a middle point from the graphs above to allow for a third point on the polar to input into the polar calculator.

This is the result:

The red curve is obviously for the Litespeed RS 4. The black curve is for the Litesport 4. These curves are an approximation. I sent them to Gerolf this week, but no word back on whether he thinks they are representative of the performance of the two gliders.