I don't use the sound tower program. I just record the MIDI and also about 100 other MIDI routings as I go in S1. Of course Reaper would be fine for that too. I just prefer Studio One. Just what are you using the Sound Tower Program for? Is this absolutely necessary to your Prophet experience? Though I tried the SoundTower program, I didn't get it. If you look at my other post I just made, in the adjacent thread (Talking about the 6th post in this thread: https://forum.sequential.com/index.php/topic,7263.0.html) --I detailed how I would if I wanted to , send different programs banks and groups (or entire USr) to the synth. I never messed with that NRPN version of MIDI I need my midi recorded It is the only way I ever played with it all I need my prophet into things, like my Advanced Scene Switcher. I can't conceive of how NRPN would be worth it for me. I will be hated possibly for being anti sales, with this idea, but it's not particularly cheap though it could be done free, but at least I don't gotta use a mouse to send these sysex to the synth.
There might be a language barrier here, as I don't fully understand what you're saying. From your other post it sounds like you're using sysex and the MIDI extension for Streamdeck. I actually use two Streamdecks in my set up already (one for controlling Reaper via custom Keyboard Shortcut Comands, and one for sending MIDI note data to a digital mixer for bus selection). I'd be curious to see an illustration of your workflow.
My reasoning for using the Sound Tower VST is to have access to the following:
1.) A fast and visual way to rename and reorder patches on the P10 hardware. Given the P10's way of dealing with presets with splits/stacks, I definitely want to be able to quickly move and organize patches being pointed to as the B layer. I'm still waiting to hear back from Sound Tower or any users here about how to do this, though I'm not optimistic based on my first reading of the manual.
I can't fully picture how your workflow would work, but I would like to be able to quickly take a patch I'm working on, duplicate it, rename in, place it in a location on the synth, and then ensure that whatever patch I replaced could be easily put elsewhere on the synth.
2.) Reaper has an option for allowing any VST parameter to have it's own LFO. This means lots of additional modulation via MIDI for the P10.
In regards to NRPN vs CC:
Unfortunately the response from Brian @ Sequential wasn't definitive. He said that the NRPN resolution is similar to CC for the P5/10 for historical accuracy (but then suggested that I compare all the CC/NRPN resolution using a MIDI monitor, which would imply there may be some different to discover with enough work.)
If the resolution is similar, using CC would be fine, but I'd still like to have a VST that will have those CC parameters (so they can be modulated via Reapers parameter LFO). Perhaps using MidiQuest? (but I have still had no luck running the program on Windows 10)
The other issue I'm running into is that I often don't want to record knob movement while recording MIDI. This is generally the way VSTs work, and I usually prefer it. The Sound Tower plugin seems to block the knob movement if you take the MIDI from it's output and route it to a new track, but it causes other MIDI issues (echo and a significant lag, which I'm reaching out to Sound Tower about).
EDIT: After reviewing the MIDI implementation PDF, there is no resolution increase with NRPN. All values are within 0-127 range (or less as per CC). The only parameters not included in CC are global functions.