I may be mistaken but the only LEO satellite that I know of that uses circular polarization is SO50, which uses LHCP for the 70 cm downlink.

I am in the process of replacing a dual band linear antenna with the M2 LEO pack.  I was thinking about setting the 70 cm antenna for LHCP and the 2M antenna for RHCP.  This would maximize the downlink from SO50 but also give me a lot of attenuation between 2M and 70 CM which would help with desense.

I have a desense problem with my current Cushcraft antenna, even with a diplexer as a desense filter.  For the LEO pack antennas I will not be using M2's aluminum boom, but instead have a 12 ft fiberglass boom.