Something i recently found out about Verbatim discs is that they are made in two places. The ones made in Taiwan by CMC are apparently inferior to the ones made by Mitsubishi in Japan. The only way to tell is to look at the "made in xxxx".
This probably explains why iv`e had some Verbatim`s with a low coaster rate and some with a high
Recently got some Sony DVD+R from the local Sainsburys (£8 for 50 i think) and they seem to be pretty good.
As to Lister of Smeg
..............do some looking up, burn speed has absolutely no bearing on reading (assuming no errors)
Here`s a good place to start
http://www.dvddemystified.com/dvdfaq.html