You seem to have two goals here. You were interested in m2ts files because it gets rid of all the previews, extras, etc which is not a bad goal for your backups. But, you want a format that's easily burned to disc when media becomes cheaper. That's also not a bad thing. I make movie only ISOs of all my BD movies. This saves space on the hard drive and gives me what I want in a backup...the movie. If I want the extras and all that, I'll pull it off the shelf. Most of the time I'm interested in simply watching the movie. In any case, if you have AnyDVD, you can do the following:
-Open
BDInfo and scan your disc. This will tell you the playlist file for the main movie. (Useful for movies that are split in seamless branching)
-Open
TSMuxer and open the playlist discovered in BDInfo
-Select/Deselect the streams you want to keep/remove
-Write it out to a BD Folder Structure
-Use
ImgBurn to create a new UDF 2.50 ISO from your BD folder structure
This will give you a movie only ISO that you can mount and play back in any software player, and when prices are cheaper you can then burn it back to a blank disc, as well.