If you can burn media at it's rated speed - with great results
by all means - do so . More power to you .
If you are experiance burning problems / playback problems
the solution often is simply reducing the burn speed .
A 'General Rule' of Half seems most effective .
16x @ 8x ( or 12x ) / 8x @ 4x
Especially if backing-up with somewhat 'high' compression ,
1:1 Back-ups don't seem to be as susceptible as a DVD9 reduced to DVD5
This 'General Rule' compensates in several areas ,
Media Quality , "Firmware" match , the DVD/RW Drive itself , 'state of HDD Defrag' ,"Player Compatibility" , "Compression" , etc.
I get beautiful results burning my 8x+R TY DVD-ROMs @ 4x.
The result is well worth the extra 5-6 minutes .
@ 8x they look good too , don't get me wrong .
In one of my players these 8x @ 12x or 16x ( MadDog ) even look good ,
but @ 4x , they play perfectly , in anything .
These are "FULL" back-ups ( Max Compression )
I'm not disagreeing with you entirely ,
It's just at times , there are more factors involved , to consider .