I read through the announcements, at least I thought I did, what incremental features are you all seeing, besides power sharing between the 280 and 380? As I recall that's it. The 380/360/350 all have 2 extra pins to allow for power sharing comm, which also by the way means if your using a tech camera, you need a new plate as the current plates don't have a wide enough hole for all the pins. I realize the 180/160 will not have all the capabilities, but that's not the posed question.
The 380 has long exposure capability, built on the same tech as the 260/360. Unless it's a totally new design, which I have told it's not, then I think you can expect the exact same results as the 260 and for long exposures, the 260 is not a great back, past maybe 10 minutes unless you are working the arctic. The 250/350 will run rings around it for cleaner longer shots. Plus the 380 is a denser chip, and may be even more suspect to heat thus noise.
Also, note that the LE mode for the 380 starts at iso 200. You really would not want to stack short exposures with this back for a lot reasons, but the mandatory dark frame is one of the main ones, so then you are looking at single long exposures with the mandatory dark frame of equal exposure, and you are at iso 200, which is not IMO where you want to be for a long single exposure, more like iso 50, especially if you are working in daylight. Note also the base iso of the 380 is now 50, not 35.
I looked at the upgrade to the 380, but I can't see a valid reason for me, coming from the 260. Yes the upgrade is more expensive by around 2K, but even if it was the same, besides the 20MP more pixels, which I don't need, I am having trouble seeing the reasons to move, unless you want the XF and all the communications. But for me at this point in my career, I couldn't justify that anymore. If the LE results are similar to the 260, again I can't see any reason for the move, the image quality is just not that good unless you are looking for 2 min to 10 minute shots and don't live in a warm climate, with humidity.
I may have missed something for sure, as I only glanced over all the specs of the 380, and once I heard it was based on the 2 year old tech of the 260, I was less interested, been there done that, never again.
Just curious,
Paul