The RS-28 can also carry 10 heavy warheads or 20 light warheads, its payload and range are similar to the DF-5C and SS-18.
The only difference is that the RS-28 has the more improved modern liquid propellant technology compared to its predecessor SS-18.
The R-36 is not more powerful than the DF-5C, you should read more analysis from
@Martian2 .
The DF-5C got thicker diameter than the R-36 with the modern liquid propellant technology. There is no reason to believe that the R-36 should be more powerful with a thinner diameter and a more primitive liquid propellant technology.