Your idea with EQ'd sends is actually a great idea. How do you set the various EQs to avoid phase cancellation? Do you add effects only on the stereo bus?
I just played with the sound. It is not ideal right now I think the bass is too loud on the left and is somewhat distorted at some points. That's just my excessive eq volume on one or more of the eqs. I spent a couple of hours tweaking the current sounds. I forgot about the phase cancelling. Someone else would probably be doing a better job using a scope or something. Probably should run a scope on it/them but that is pretty tricky stuff for me I am just going with what sounds good to my ears. I went from L to R in a even distribution mathematically, then I focused on different notes of the keyboard (on one particular program) when I set the frequency for each eq. I'm sure it's not perfect.
I have a few different listening points the headphones, and a pair of speakers coming from either side of a room.
Beyond sustain and stereo field, a reverb can add colour to a sound. Nevertheless, I understand that in your DAW you are still able to add colouring by reverb on a dedicated track.
When you do it with the EQ you are trying to spread out the sound on a frequency basis like some synths that play in stereo spread the sound on a voice by voice basis. This gets muddied by any FX reverb anywhere in the setup. That's why I took it off.
As a general rule, with mid-side processing (which is pretty much what's being discussed here) it is considered a good practice to send all the lows down the middle.. you might find some happy accidents outside that consensus, but overall most agree that maximum creative flexibility exists in panning mid-highs and sending lows up the middle.
As far as reverb -- there have been some great plugins emerge in the last few years that I will mention here. Strymon Cloudburst and Eventide Blackhole Immersive, for those seeking that particular kind of sound, are better than much of the free or cheap stuff out there. Despite all progress plugins have made in recent years, I still think some pedals just, plain and simply, sound better. Examples are MercuryX (more for dreamy stuff but possibly my best overall), OTO BAM (one of my faves for vintage sounding reverb, currently on my P10)... notice these are not cheap pedals.
One of the reasons they sound so good is the curated nature of the reverb algorithms -- someone has already spent a lot of time figuring out specific formulas for a mono signal and how to send it out panning in a particular way, and those presets can sometimes be a defining instrument characteristic. If a guitarist picks up a Gibson Les Paul it sounds different than a Fender Jazzmaster, because of specific curated design choices made along the way. I see specific pedal algorithms as similar in that way. Sometimes it's about searching for a specific sound, and other times it's about a specific sound finding you, and inspiring you to build upon it.
If writing songs is your thing I wouldn't get too caught up in the particulars of all of the above. One of the reasons the Prophet 5 was so popular in the first place is that tracks got recorded mono, then multi-tracked to produce different vibes. We live in an age of "instant gratification" where we want those instant vibes out of the box, but if you track audio in mono you actually have a lot more options with what you can do with it later than figuring out the ideal path of the stereo signal in.