Do you know if it is multithreaded deafeyejedi?
It is...sort of. It can process multiple frames at the same time (in separate threads), but it will only do so if you actually ask it to, i.e. if you actually try to read both DNGs at the same time. If you're reading the DNGs from a post processing app that supports "pre-fetching" or loading multiple frames concurrently, then MLVFS will be multi-threaded. I know SpeedGrade supports this and there's even a setting where you can specify the number of frames it will "pre-fetch" (it's a good idea to set it to the number CPU cores you have for this). If you only try and read one DNG at a time, then MLVFS is only going to use one thread to process that DNG. An example would be the Finder, if you use the Finder to copy files out of MLVFS mount, it only copies one file at a time. If you wanted it to be "multithreaded" you could start multiple copy operations (for example start to copy out half the DNGs, and then start to copy out the second half).
Now, I suppose that I could support "pre-fetching" internally to MLVFS => when one frame is asked for, go a head and process the next one (or the next several) in a separate thread, so it will be ready when it's asked for, but that will be some work to implement.
If you rather use MLVFS -- you just gotta apply the black/white levels and/or adjust the exposures manually
That is not true. You should not need to adjust the black/white level with MLVFS. If you have an example file where MLVFS gives the wrong black or white level, then please share it with me so I can fix MLVFS.
As far as manual exposure/highlights adjustment goes, I've never met a dual ISO image I didn't need to make some sort of manual adjustment anyway. In fact, that's sort of the point (to have lots of ability to push the image really hard).