..My LG RH750 has four recording speeds 1hr 2hrs 4 hrs and 8hrs....even the 8hrs mode is good enough for me for normal veiwing ....I use the second best for anything I want to keep and only use the best quality (which is superb) when something like a good class film is on tv and then to the 80GB hard disc.......This machine also handles double layer discs so that is 2hrs at top quality if needs be.........
...for 230 quid ....it's a beauty.....commoner.
To answer your original question...It will not allow "dubbing" unless there is room on the disc so I have to drop the quality setting to suit. Just using the timer or one touch recording method, the recording stops when the disc is full.