PKO and Palm are not interchangeable, by a long shot! As someone else pointed out, Palm is more in the same "family" as lard or tallow, and yes PKO is more closely akin to coconunt oil. Personally I have used both in the same soap, and I love the combo. PKO has a different feel in soap than coconut and I love it. I do personally prefer a lower cleansing, but there are other factors to consider.
If you want to get your cleansing numbers down, use less of them, but yes you can also increase your superfat to help compensate. Again, soapcalc numbers are only a guideline, they are not infallable or carved in stone.
I also do not recommend the use of grapeseed, peanut, canola, or shortening in soaps. I know, I know! A lot of people use them without a problem, but I personally do not find that they bring anything special to the party and they can increase the risk of DOS. YMMV of course, JM2C