Even though
@chrfr is right and not every print designer needs a Mac Pro, I've always been using "Tower" Mac Pros at work for print graphics design. The only reason that I switched to MacBook Pro models was that there were no more serious towers available since 2012 and portable Macs became quite powerful and yes, they're practical to carry around, too.
To be honest, I don't like iMacs, except for some relatives that just do sparely know how to handle a computer. They get a system that has a single power button, plenty of ports with no need for adapters and it just works as long as it works.
Maybe the display of an iMac Pro can show true 100% of AdobeRGB colors and almost the full spectrum of the more often used CMYK output profiles. However, I bet it's still a good idea to compare even the upcoming Mac Pro Display, that surely will be a great hub with a great display that makes non color critical work far easier. Compare it to some wide gamut reference display from companies like NEC or Eizo.
If it's not the money that hurts, just buy the most powerful Mac Pro for your wife ;-) No, just kidding. Ask her, how often she gets into situations, when she has to wait for her Mac while rendering some weird Photoshop filter, saving or reading some tremendous big file or publishing some gigantic PDF. If she likes the breaks for a coffee or tea, she might not need a faster machine, but if she's got critical deadlines often like me, she might be pleased about a lightning fast Mac Pro.
Putting a Fusion Drive into an iMac or inside whatever other new Mac, I'd say, that's a waste. Indeed, there are some two drives in a Hybrid Drive, one SSD and one HDD paired together. That makes sense in an iMac of 2006 or something similar to a 1.5 Gbps Serial ATA or slower that just can't really benefit from the full speed of a pure SSD. All new macOS systems as well as most recent (heavy) software packages can actually benefit from the extra speed-gain of a SSD that doesn't need to grab data from a mechanical drive from time to time. One of the best part of it, is the silence of a SSD. Just make a comparison and stop the time for opening 5 or 10 apps straight after another (better select them all at once and press Cmd + O) on a system with SSD and on a system with Fusion Drive. Then stop the time to boot. I never want to go back to HDD, except for backup purposes or in a RAID setup, but even there no FDD, but pure HDD. Another culprit is that Fusion Drives sometimes can behave strange, giving more occasions for errors or unexpected incompatibilities. Do you a favor and spend the money for an internal SSD as large as you want to afford.
And finally: just buy this new iMac (Pro) if you really like it 👍
