the TL;DR version of this: no, I wouldn't!
Caution: long post following
My original hardware setup up until some 18 months ago consisted of a Kurzweil PC3 or PC3K alternatively (I've got both of them...), plus a Yamaha Motif XF6 on top. Nice and universal setup, but heavy. Plus, editing on the Kurz is not a lot of fun; it's pretty convoluted.
So, when Cantabile 3 came along, I decided to to the full software route - and TBH, I haven't looked back! Especially the concept of songs and song states, with full configurations ready for total recall and my big "red button" to take me from one state to the next, is just a pleasure to work with on stage.
For the first phase, my ambition has been to really get my setup reduced to just one master keyboard and a guitar - no footboard! When playing guitar, I have my patches set up as song states, and I use my piano hold pedal to step through the states - simple as that; no more pedal tango . As a master controller, I still use my Kurzweil PC3K - simply because it is there, and the keybed is a joy to play on! Also, its nine long and solid faders are excellent for controlling Cantabile parameters - I just wish for some more buttons to control some Cantabile and LivePrompter actions.
The only downside to the Kurz: it is HEAVY - 24 kg plus flightcase . So I'm always looking for an easier-to-carry alternative. For some time, the Arturia KeyLab 88 was high on my list - nice-looking, good set of faders, knobs and pads, a decent Fatar keybed, and a significantly lower weight make a good package. But I've heard a number of user reports on flaky build quality, with keys failing after some time, which made me a bit apprehensive. The other alternative for me would be the Native Instruments Komplete Kontrol S88 - same Fatar keybed, even a bit lighter than the KeyLab. The only downside to this: no faders or pads, just some rotary encoders. A number of other 88 key master keyboards fell from my short list, since they don't provide aftertouch, which is a must-have for me.
Currently, I'm in the process of expanding my setup with a small secondary keyboard - it's just a bit easier to have your solo sounds or some special effects on a separate keybed instead of having to split or layer. And organ solos on a hammer-action keybed are a bit strange... But since I only need a controller keyboard, I simply got myself an Alesis VI 49 for this task - very cheap, small and light, which now sits right on top of my Kurz on the second tier of my Spider stand.
Due to the fact that the Alesis has such a small footprint, I didn't have to move my Kurz down, so my lower arms are still in an almost optimal playing position when standing. My keyboard rig does look a bit top-heavy (I'm 1.88 m tall), but it's a joy to play - and as the band's lead singer, I'm not going to sit down for a gig...
My pedal setup is simple: just a dual piano pedal (Fatar VFP2) and a yamaha FC-7 (very nice pedal for playing standing up, since its angle can be specially reconfigured for a standing position).
One thing I've learned with my single-keyboard setup is that in many cases, layered sounds are far easier to manage and play than splits. I frequently simply layer sounds on top of each other and blend between them via the expression pedal or the mod wheel. Works nicely for organ layers on top of a piano sounds, but also for the occasional brass riff - simply press a pedal for brass and release to go back to piano.
My recommendation would be: if you have a decent PC in your (home) studio, try setting up a couple of "software-only" songs in Cantabile with your existing keyboards, using them just as controller keyboards, so that they are easily replaceable by whatever future solution you may choose. Use racks to abstract away some of your keyboards' features like faders, knobs, buttons (e.g. a "faders" rack, translating your keyboard input into standard controllers, that you can easily re-configure when your master keyboard changes). Use songs and song states extensively to really automate your setup to get the most out of Cantabile.
I would also recommend to set up a "universal" song with just a couple of basic sounds (piano, epiano, hammond) and a means of switching between them quickly - this is super-helpful when you rehearse some new songs and you haven't had the opportunity to set up specific Cantabile songs in advance.
When you're happy with the software side of things and you trust the setup sufficiently, you can then decide what hardware changes you want to make - invest in a new main masterkeyboard or a secondary controller, or maybe a separate controller like a Novation LaunchControl. Also, based on your experience with this set-up, it will be easier to decide on the right configuration of your "brick".
If you don't have a powerful enough PC in your studio, I'd recommend going for the most powerful "brick" you can afford to start your setup - with the u-he line-up and other instruments, you can't have too much horsepower. If you're heavily into sample-based instruments, setting up your "brick" with tons of M.2 SSD space will dramatically reduce your load times, which may actually make it practical to switch samplesets between songs, instead of simply pre-loading everything you may need.
Hope this helps!