The 3500 still burnes better with cheap media.
With A-grade media the difference is very small.
Here is a burn on the 3540 with RitekR03-02 burned @ 8X:
And here a scan from the same disc burned with a 3500 also @ 8X:
As you can see both scanned with my LiteOn drive to rule out the dodgy scanning of the 3540. (media is Platinum DVD+R 8X)
I have both drives in my pc, but i tend to use my 3500 a bit more then my 3540. Because i mainly use cheapo media.