Test driving this plug-in, I quickly appreciated the ability to add or subtract distortion by switching it on or off. This increased focus and adds a vintage vibe and roundness. I felt the MP5 has a clear sound even with extreme boost or cut. More important, the user interface is crisp and easy to see, as well as get around.
In terms of comparable analysis vs. a real hardware tube eq, I didn't have that opportunity. I would guess it is close with regard to the eq curves available but the anomolies of pure tube audio are very complex to model, even in 64-bit.
Overall, the MP5 does the job well. Thickening kick drums and bass guitar. Enhancing and scooping mids on guitars. Adding high frequency without harshness. All a win with this plug-in.
Would I use others, maybe. I will find many uses for it and the precision of the interface makes it fast and efficient.