On the bright side, after a fairly mammoth bug-killing session, the movement paths are now working as I want 'em.
So you can place path nodes around the shop, set various attributes (like whether their interval is curved or uses straight linear, how long objects take to traverse the interval, etc) and view the path in the editor. The dotted lines are curved intervals (all of them in thsi pic). If you want more control over the shape of the curve, you can use custom control-points instead of just usng the next/previous nodes in the path.
You can manually enter the time to traverse the time interval, or push the "Preserve Previous Velocity" button to automatically calculate the time based on the speed the object was going at when leaving the previous interval.
There's also different types of paths (end-to-end, with reverse or with loop-back) which will hopefully serve to allow me to create mario-esque moving platforms that repeat their movement paths or loop back on themselves.
The last feature here is that each path interval can have movement effects added to it to make the movements look more natural. For example "slow-to-rest" causes the object to begin the interval with some speed, but then slow down to a halt by the end of the interval.
Woah, quite an essay there. Anyway, a bit more testing to make sure all the features are working fine, then I can move onto the next connundrum which is getting the automatic LOD working. Should be fairly simple as I already have the code for creating the different tesselation levels, just need to save them for use at runtime and define the distances at which they switch.