Hussar
Legend
I guess that's the point I was working towards. It's a single section, and not a particularly long one at that - the earlier sections took much more time to play out - and it's a chase scene. A chase scene is extremely hard to do well and is linear by nature. The suggestion to "keep the macguffin out of the player's hands as long as possible" is perhaps bad advice (although not unredeemable) but, if you ignore that sidebar and simply let things fall where they may, it works fine too.When I criticize DH for being a railroad, that's predominantly because of the Chase chapter (which is a pretty important section of the adventure). The other sections are largely either freeform or at least not any more railroady than any other adventure. But that Chase chapter is something else. It doesn't matter how good (or bad) rolls are; it doesn't matter how clever (or dense) the characters are. The same thing happens regardless.
IOW, for me, it was a single session out of a module that lasted a dozen sessions, thereabouts. Meh, not something I get too tied up about, and, frankly, there's no real way that the players would know any of this anyway unless the DM gets really heavy handed about it.
So, in my view, you have a significant portion of the module that is pretty wide open, with a single session that's very linear that directly connects two other sections. Of course it's going to be railroady. Writing a chase scene like this that directly connects two parts of an adventure will always be a railroad.