I put myself up to it, and worked on the solo RP for a bit over an hour, with a little time in there to code up oracle rolls, which are basically just percentiles where sometimes it matters if the digits match.
There were some nice twists and details in what I got written. (Although, I just noticed that I should have ended with a Compel. I need to have a better handle on all of the moves.)
I think maybe I should contrast this with my earlier attempt to use Risus. Now, I got further with Risus than I have so far, but thing going on with Risus is that the NPCs are constructed pretty much like the PCs, which isn't too cumbersome from a bookkeeping perspective because you could fit several character sheets on an index card. However, it does mean that the GM is somewhat expected to run NPCs like a stable of PCs, which turns out to be kind of awkward when the entire game is one person doing a bunch of mental juggling. Some of the commentary I've seen on Ironsworn points out that NPCs can't use combat moves, which is fine by me, since it gets rid of some weirdness I encountered running Risus solo.
Although I suppose part of the weirdness I hit is down to my general tendency to forget that writing things down is a thing. Maybe if I'd actually determined an initiative order...
In any case, this is feeling good so far, and I'm gratified that I actually got some amount written. I'm going to call the entry a little early and read for a bit, because I don't want to take things up to or past the wire again.