What would you do ?

If you had the chance to get a Voyager RME for $1500 with all the upgrades, would
you get that or the Little Phatty to go with the Voyager ?

I would always prefer the keyboard version of a synth.
I noticed, that editing a synth module is half the fun as sound design and playing on a single unit.
But this is a personal preference of mine.

So it sounds like you already have a Voyager. I would agree with getting the LP since it has a keyboard and might be fun to “take with you” on a trip someplace, etc. where the Voyager itself (or the RME) might not.

I have the SE and I picked up the RME for the $1500 brand new with version 3 hardware installed. It was hard for me to pass on it since I saw one used for $1700 that still needed the v3 upgrade and the fact the LP was only $200 cheaper.

What surprised me the most was how different they sounded from eachother.
The saying that no 2 Minis sound the same applies to Voyagers also. When playing the same patch on both you get a different tonal quality and if you play them together they blend nicely.