Not sure about express, but Ultra can verify the speed of your media, and you can force it with other software (like PrimoDVD), but if it's testing lower, not a good idea to push it, especially if it's testing well below 4X (high 3.xX should be ok). When I buy OEM disks for one offs and bakcups, stuff like the Fotis or Minis gets high 2.xX (2.8/2.9 mainly) in speed tests on my burner despite being rated for 4X. I have never had a problem with Maxell, Memorex or Verbatim, NEVER, not a single coaster or corrupt video. Funny the Fuji's I've had have been ok, they are 4X +RW, so not quite the same.
Two things come into play here: first, Sony's older drives (DRU 500 series) were notorious for not being able to burn 4X until they got a firmware update, doubt that's it, but may be something similar they have to revisit later; second some of the 'older' 4X media doesn't play well with some drives, which is likely what's happening in my case for the OEM stuff.
For more info the 'source' for me is here;
<A HREF="http://www.dvdrhelp.com/" target="_new">http://www.dvdrhelp.com/</A>
If anyone knows, likely someone there does.
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