Nec 2500 vs 2510

This is not about which to buy, but an experience I had with them. I was making a backup copy of one of my movies last PM. on some verbatim 8x on my 2500 (107v2b5 wanted the ability to write ritek 4x @8x) finished copying, played in my standalone and it skips. Thought I got some bad discs(Best Buy has 50 for $40) anyhow they said cmc something. So I then copied the same files on to my 2510 @ 8x and no problem. The 2510 has 2.16 firmware on it. is this a firmware issue or something else. should I flash the 2500 with 2.16 or 2.06 if so do I have to flash with 2.15 the 2.16 or can I just flash the 2.16.

Firmware V2.16 seems to have better write strats.
You can flash the ND-2500 with this firmware but you will need to do it from DOS, remember you will lose bitsetting with DVD-R DVD+RW discs without herries firmware.