If you do a search on this, you'll see a lengthy thread that had noob_pwn and me at the helm, along with several other heavy hitters on this forum - discussing the pluses and minuses of the P50E within the FatBottom and Deliverance cab. I've opted for the Deliverance 4x12 due to the fact it's being driven by a very tight, dry amp/preamp set up. I wanted a bit of spank and sizzle in the cab, not just surgical precision and hi-fi. Here's an excerpt that you may have already come across, but otherwise, use the search function on this page and you'll get a mess of goodies relating DIRECTLY to your question.
FWIW, I was skeptical about the P50E's, and furthermore, they're notorious for sounding a bit like ass for the first 40+ hours before they're broken in. It's AFTER they've been broken in they apparently sing like none other. I've got my new Deliverance doling out "MP3's" at 50% volume in an ISO area to break in - I'm serious. Once that's done (tomorrow), she'll be re-tested and I'll be able to hear - if any - and more than likely - the difference.
Here's the blurb:
The P50E speaker is custom built to SFD specifications by Eminence, and is only available from Steven Fryette Design, Inc. The P50E is not an OEM version of the Eminence Redcoat or Patriot series speaker lines.
It is difficult to discuss the sonic characteristics of the P50E or any speaker for that matter, in isolation because so much of speaker behavior depends on the environment in which it is operating - that is to say, 2X12 cab, 4X12 cab, front-mount, rear-mount, wood type, construction style, playing volume, etc, etc. Having said all that lets talk about the P50E versus the popular Celestion Vintage 30 in a Fryette 4X12 FatBottom straight cab.
The P50E is actually a 50-watt speaker. The V30, although officially rated at 60 watts is in reality closer to 75 watts. The P50E has a smaller magnet than the V30, which insures that the speaker will break up at lower amplifier power than a V30. However, the V30 has a more compliant suspension, which together with the larger magnet causes the speaker to move more-low end. This also causes more distortion in the higher frequencies contributing to a harsh top end. The highly compliant suspension makes it difficult for the speaker to track low frequencies especially at high volume levels and this causes a “woofy” sound when playing staccato chording (‘palm muting”). It is also partly why the P50E, although lower in power handling capacity, seems to produce about as much low end as a V30, yet with better control of the low end. The smaller magnet on the P50E also contributes to a softer, more natural sounding high-end response, which is not smeared out by the sloppy suspension, as is the case with the V30. Finally, the Fryette cabinet is a front loaded type, producing a more open, well-dispersed sound. Front mounting a V30 is less desirable as the harshness on the top end, which is normally masked in a rear-mounted enclosure, is now more audible.
The result is that the P50E, while not a particularly scooped speaker, can sound a bit that way in a Fryette cab, or more like a tighter, smoother V30 with a more focused low midrange. Now take those speakers out of the Fryette FatBottom cab which does a good job of controlling the speakers bottom end response and put them in a traditional style 4X12 enclosure, which does everything but control bottom end behavior. Now the rear-mounted P50E will lose some top end clarity and the bottom end control will be diminished, causing it to sound much more like a Greenback but with a little bit more spank. The V30 by comparison will sound smoother on top, but the low-end difficulties will be highly exaggerated.
Another very important consideration in the comparison has to do with the age and condition of the speakers under test. The P50E is not factory “preconditioned” as many OEM speakers might be or might claim to be. This means that depending on usage, it may take as little as a month or as long as 6 months for the speaker to “break in”. A V30 will be looser and warmer out of the box, but also is brighter and tighter than it will be 4 months from now (with regular use). The V30 will mellow out a bit over time, but the low-end control issues will be exaggerated. By the same token, the P50E, while retaining good bottom end control will sweeten up and smooth out over time.
Comparing the FatBottom to the Deliverance cabs, the FatBottom series cabs loaded with the P50 speaker is considered modern sounding and exhibits lots of projection, low-end control and excellent tonal detail. The Deliverance cab on the other hand will sound warmer, looser and sweeter than the FatBottom cab even though they use the same speaker. The Deliverance cab is designed to make the speaker fatter and warmer sounding, as might happen in a traditional 4X12 cab design, but without the traditional boomy, sloppy rattling low end. The ability to identify and manipulate key elements of cabinet construction gives us control over those speaker parameters we wish to suppress or enhance.
The difference between front mounted speakers and rear mounted speakers is subtle and both methods have their pros and cons. Overall we find front mounting to be preferable. Those who would disagree must realize that it is difficult to compare based on the sound of other manufacturers cabs because construction method and material type/quality play a much larger part than mounting method in determining the sound of the cab and behavior of the speaker.
Finally, all of the above depends on the amp in response to which the speakers’ mids, top and bottom will all shift around in concert with the difference in behavior between 100 watts or 50 for example. Keep in mind that this discussion assumes all speakers in the comparison are 16 ohms, as the P50E is only available in 16 ohms. This is important since the impedance of the amplifier load will dramatically affect the behavior of the amplifier due to damping factor and frequency response.
V.
I would assume this is also why Killertone has kept his cabs and just reloaded. The quality is on par or better than all the best cab makers out there IMO. 
Motherfuckinfuck. I realize it's not a volume war but it would be nice to at least be heard. 