I mentioned a few weeks ago I I bought a Pioneer 111d and a NEC ND-3550A.

I just got done burning about 75 Dual layer discs and 75 single layer discs.
The dual layer discs were Verbatim 20 DVD+R Dual Layer Inkjet Printable. They are rated at 2.4X yet users on forums and Nero report they can be burnt at 8x.

I attempted a few burns at 6X and had two coasters on the Pioneer. I then burned at 4X on the NEC and the Pioneer.

I also burned a bunch of Taiyo Yuden 16X DVD-R White Inkjet Hub Printable at 8X. the TY’s burned perfectly at 8X in both burners. I printed the discs on my Epson R200.

Overall I am quite happy with both burners. I have a little more confidence in the NEC burner than the Pioneer. I have absolutely no justification for that statement. There were no controlled tests and I also did not attempt higher than 4X burns in the NEC. If I had maybe I would have gotten a few coaters as well.
You can’t go wrong with either burner.