DLs are about 8 to 10 times more costly than Sls. Compressing does cause some quality loss to the end product. Spliting to two SLs is also a lower cost alternative without quality loss.
It's usually the price factor for poor folks like me, LOL!
You can still get near original quality using single layer dvd-5 media. I usually do Main movie only,only AC3 5.1 english only soundstream,and cut out everything else. This makes the backup automatically start when inserted into my dvd player-no menu to mess around with or looking everywhere to find the remote. Make sure you use quality media,and a 4x-8x burn speed.
Lots of programs can do this like free dvd shrink. Dvd shrink is outdated,no updates in a couple years,but still an effective compressing program for single layer backups. It also has quality enhancements for the backups that still have compression to help with the quality.
Quality is up to the individual.I have some highly compressed backups like LOTR and Harry Potter series,and they still turned out near perfection with the 40+% compession that they had.
DL backups?
1)Gotta watch out for what programs you use. What works good for single layer backups,may not work so well with the DL's.
2) Stand alone player compatability will be reduced-guaranteed. Best to booktype the plus format DL to dvd-rom,if your drive has that capability.
3)Options of available blank media are reduced for DL backups:Like the ability to get the taiyo yuden watershields,Lightscribe,and a lot of inkjet printable media in the DL formats. Not as many options as compared to single layer.
4) Gotta watch out for brand names,just like the single layers. Verbatim is among the best dl media out there. Ricoh and Ritek are slowly improving. Dvd-rw drives may be picky as to which one of those brands will work-or you'll get an illegal disc message. Stick with verbatim.
