Nope ... Gravel, PFS (what I have), dirt .. don't think it makes a difference. The "tough" part with starting an RCS tank is providing enough food naturally. Newly set up tanks don't have microbes, algae and bio-film a mature tank has. What I did was get an LFS DW already in a tank plus a piece from my 75gal as I knew both had to be full of stuff for the RCS to munch on.
I usually give new plants a H-peroxide dip, but in a new RCS tank again, the LFS plants have bio-film on them. I do supplement crushed flakes, Bloodworms (they love those) and algae wafers. Still RCS munch constantly!