"Special Note: About the Audio Demos: "20HZ-FLAT-P-N.mp3" is flat, then the Pultec hardware, followed by the Nebula version. "100-BOOST-CUT-P-N.mp3" is the Pultec hardware followed byt the Nebula version. We hope that you will find this treasure to be a welcome addition to your collection of programs and find it useful on everything from sweetening high end to warming vocals and tightening bass response."
I agree with Enrique here, this damn thing is so close that the 10-20% difference (difference doesn´t mean better or worse) is less important than the engineer decisions taken on a mix or master. When I mix with nebula I feel I´m using real hardware results-speaking.
Greetings and sorry for this strange english I´ve written