My experiment has borne itself out. Jades do not do well in sub-irrigated planters, at least not for me. The pair of plants I had in the SIP never looked happy and now are collapsing.
I took them out today and repotted in a sandy mix. The two other plants I had earlier in regular draining pots with sandy mix are doing fantastic.
And my row of little babies on the mudroom windowsill just grow quietly without any fuss. They have salt exuded on the leaves (at least that's what I think it is) because a few times I forgot to give them rainwater and gave them tapwater....
and this one now-dying leaf on the right looks like it's produced another four or five plantlets again! I really need to stop growing these things.