Hi,
I have used Sig Lite Coat clear and found it to have different sanding characteristics than Sig Super Coat clear. Also, Super Coat clear with Dave Brown's "Flex All" added ( about half of what the instructions suggest) also have different sanding properities.
The Lite Coat and Super Coat with "Flex All' added wanted to roll up under the paper when I tried to dry sand them; wet sanding is OK, however.
As usual, YMMV!
Jim