I am definitely interested in getting a Pro 3 to sit next to my Prophet X. Same reason I eventually did go for a Drumbrute + several stomp boxes: I don't like using the P X for "bread and butter" synth (percussion) sounds, feels a bit like a waste. The P X is a wonderful instrument to blend samples and "natural" sounding instrument and real world sounds with synthesizer voices, filters and effects. Something I already tried to do on my old trusted Akai S5000 years ago. Recently I added some church organ samples to my Prophet X user library. They sound truly amazing, especially putting them through the stereo filters and modulating the loop point and start / end using an envelope or an LFO.
I will use the Pro 3 as another voice(s) and new ways designing sounds to include in my tracks. Although the P X does have a whole set of single cycle wave forms, it doesn't provide the wave morphing capabilities of the Hydrasynth (which I do have on order) and the Pro 3.
I do want to see later this year if Dave and his team will also bring out a Pro 3 desktop, as I don't have space in my studio for another keyboard. Seeing the videos and photos online, both Pro 3 keyboard editions look stunning. I will ask my favorite shop in the Netherlands to setup a demo for me so I can try out the Pro 3 in the next months.
Just keep in mind that I want to play / compose DAWless, I use my DAW only to record and mix/master the recording.
Last but not least: the Pro 3 is a Sequential product - it would be my first "Pro" flagship mono instrument from Dave's team. So I got to have it of course ;-). I will create the space in my studio somehow regardless.