The main thing is you want good drainage. If you got some Canadian peat and some coarse sand and added that to your perlite, you should make a decent mix. I have 30,000 cycads in pots and I use:

40% Canadian peat

30% coarse sand

20% cypress sawdust

10% perlite

My personal choice would be not to have any mix that is 40% peat..., especially not a cycad. Nothing wrong with the coarse sand, perlite and turface, some humus, and I also incorporate a generous amount of mix made for epiphytic orchids and bromeliads. As noted above, you want a mix that drains well. The problem with peat moss based mixes is that they stay too wet but then, when they do dry out are almost impossible to remoisten.

Many people have their own ideas on their mix. All I can say is that I have used this mix for 26 years and have gone through over 600 yards of it over the years and I have never had the problems he mentions. I'm in Florida and we get 4-6 inch rains in a day, and I have never had a rotting problem, and the plants grow very well and very fast for what people think cycads should grow. Depending on the species, and along with my fertilizer, I have had landscape sized cycads put out as many as 4 to 6 flushes of leaves a year.

I think it is difficult to give a general mix for even a particular plant because of different growing circumstances. Plants growing outside, in Florida may succeed in mixes that would not work for some growing the same plant indoors, in a city apartment.

My plants go outside for the summer (Cycads, palms, Citrus and others). A few years ago, I used a commercially available peat-based mix on the Citrus. Big mistake. No, NOT ROTTING..., opposite problem, peaty mix got baked in the sun and you could not water them. I could stand there with a hose for hours and the plant would be bone dry and wilting. Had to replant all of them, so now I am on somewhat of a crusade against peat-based mixes. In an apartment btw, the same mix may work as they do not get sun baked AND you have control over watering. So, there are multiple factors to consider. Plantsman, your mix might have worked because of some additive you provided that changed the properties of the mix that prevented the peat from becoming 'hydrophobic' (maybe that sawdust). Which I would probably add to if I had access to it.

Your exactly right. It is the combination of everything together. I know exactly what you have been talking about. I had the same problem when I experimented with a coir mix. It's like the water bounces off the medium, and/or, just runs down the sides. I think mine works because it isn't 80%+ peat. It is only 40%. The sawdust is organic, but doesn't have the water holding capacity, as well ad it doesn't breaks down real fast. The 30% sand helps, but I didn't mention that I try to buy "well point sand" which is something most people have never heard of. It is extra coarse. Perlite helps a bit, you could add a little more. To be honest, I add sand and perlite for horridus and the other blue things from that area, when needed, but we are only talking about a sago here, which is really tolerant of various soil conditions. I didn't want to get to technical for such a common, easy to grow cycad. Now Zamia puesdoparasitica, that's a whole other thing.