prices of blank media now is so rediculasly cheap treat a dvd-r as disposable and you only lose 16p
I have had no problems burning at 4x (movie) 6x (data)( i never burn at max speeds on any dvd).On the Tuff disc dvd-r £15.99 for 100 you will also find very cheap rewritable dvd's that will do as you require for very little cash
http://svp.co.uk/acatalog/