I have had the chance to test some media burnt with a Nec 2500A and a 3500.
The firmware for 2500 was Herrie 1.07 beta 5.
The one for 3500 was Herrie 2.17.
Scans by Kprobe 2.3.0 on a Lite-On 166S (so take it with a grain of salt).
Here we go with a Ridisc Ritek G04 burnt at 4x.
First comes the scan of the 2500 and then 3500.