I think it's a great new feature of FSX to have the extrusion bridges in the sim now.
I love the things. My project includes seven bridges; three of them are fairly short. But the other four come are a pair of straight bridges at 2.81 miles and 2.7 miles; a stretched S-bend bridge 4.6 miles long; and a stretched out C shaped bridge at 2.36 miles (pictured above). Those are some pretty good sized bridges and I've never made a 3D model of something that big. And I once did an entire international airport. But that could be made in chunks and assembled. Even then, the only parts (the runways) that came close to that big were just rectangles.
Are the extrusion bridges perfect? No, they're not. There's no decks or pylons that match what I need and I can't realistically put enough pylons to mimic the real bridges. I think if I put as many as I need, they won't display. But I figure they're close enough. Not that I'm lazy. I'm just not sure I want to put that much work into them. Of course, I'm going to try to get the extrusion bridges to be as good as I can (that bridge there is too tall right now). Maybe later after I've finished the new islands, made four lighthouses, two visitor's centers, filled three marinas with boats, and two geological features and released it I'll revisit it and do the bridges properly (as well as go back and do a few things I've scrapped like fisherman's pick-up trucks parked on the beaches).
If anyone's curious what exactly I'm doing and what I've rambled on about, I'd got lost flying VFR along North Carolina's Outer Banks because one major landmark, Oregon Inlet, was missing. So I got cracking on that, then realized that the whole place was pretty bad. Thus was born my project to rebuild four major islands of the Outer Banks (Cape Lookout and Bogue Banks were cut, because I've never been there). Really, for the place where
Kitty Hawk is, I'm surprised how inaccurate the area is. KFFA itself is pretty well done, but even the immediate area around it is bad. For instance, the Wright Brothers memorial is on top of a huge hill, but in FSX its just sitting on level ground with no hill.
Without FSX_KML, I don't think I'd have ever started this crazy mission.