Ah, that's a good idea. Haven't experimented with PreParse before, so I'll take a look at that.
There could be other problems - e.g. in one situation, I was enabling and modifying an STM and rebuilding it at read position 0 and without autoread, so I could manually read it at a later frame.
I was able to work around that by not calling Rebuild myself, setting currentReadTime and autoRead separately, and allowing it to rebuild on enable. It worked in this case, but the downside is that I would be committing to setting autoRead to false, which may or may not be what I intended.
Generally, I think I was able to work around the situations that came up for this specific scene, but it feels like it could become awkward quite easily.