Actually, the Director reports that prior to the formation of the National 594 Soapbar Department he had two CU22 Soapbars, both with maple necks. One had a RW fretboard, the other had a maple fretboard. The maple fretboard model belonged at various times to the director and to his son, during the period from about 2000 - 2014.
Your Director has also had two McCarty Soapbars, one with a mahogany neck, and the other with IRW. The mahogany version was in the Director's stable from about 2001 - 2009, and the IRW neck version was there for probably 3 years during the same period.
All 4 had the earlier Duncan P-90s that PRS deployed. All four had the 25" scale length.
Of course, there can't be a true scientific comparison between them, since the McCartys were stoptails, and the CU22s were trems, and other features were different. In addition, the scale lengths and bridges of all of them were different from the current one.
Nonetheless, your happy-go-lucky Director is definitely that guy who'll wade in and express his usual subjective and anecdotal opinion garnered from comparing the older guitars.
The maple/maple CU22 Soapbar had a very fast attack with very solid fundamental tones, and very crisp low notes. The director appreciated its direct crispness, and its brighter character. The mids and upper mids were characterized by a "flute" resonant sound so typical of maple necks, especially on the neck pickup.
The maple/IRW CU22 Soapbar had a slightly slower attack, with a bit less twang. The overall sound might be described as warmer. The director didn't have this one very long, but not because of the tone. That's just the way life was in the director's whirlwind of guitar comings and goings back then.
The mahogany neck McCarty Soapbar was significantly warmer. There was lots of clarity and sparkle in the upper mids, with a less crisp bass note tone than the CU22 Soapbar, however, the guitar was very "traditional soapbar" sounding and expressive.
The director owned the 2004 or 2005 NAMM IRW neck McCarty Soapbar. This guitar was very lively and crisp, like the maple/maple CU22 version, only with a fatter low end, and less of the hollow "flute" sound in the mids that the maple necks had.
All of the above guitars were played through the Director's amps of the period; a smattering of Mesas and Two-Rocks that were in the Director's studio for long enough that all of the guitars were played through the same amps.
The director now has different amps, and a different studio, and doesn't have the other guitars to compare the 594 to. In addition, the 594 has Vintage Duncan pickups, and the others had the brighter, hotter Duncans from the "oughts". So the Director must refrain from speculating how all this stuff would work with the 594.