And finally, one could tame it visually, bringing the branches in pre-folded to the preferred level, and with a preferred colour-scheme, by exporting from OmniFocus straight to the native iThoughts file format.

Perfectly feasible, and it's possible that Craig Scott, the iThoughts developer, may do that at some point – OmniFocus import is apparently somewhere there in his list of things to look at.

(In the meanwhile, I may do an interim sketch of it if I get some time in the next few weeks).