Well, it's been nearly 2 weeks...so whaddya think?
I ordered it while I was packing stuff and preparing to move houses so I only had the time to plug it in to my Headrush Gigboard to check if the electronics were OK.
From what I've heard there is not a huge difference with the previous model. The Bartolini pickup in the neck position seems to sound more bass-like than the EMG though. I mean, I wouldn't use the old model purely as a bass (but I never intended to do that) whereas the SRC6MS is quite pleasing through headphones and an SVT model.
In the bridge position or with both pickups and a dual-amp model with high gain, it sounds a bit more articulate than the old one, but that may be due to the strings being newer, I'm not sure yet.
Both instruments are the exact same (light) weight. The non-MS version's ergonomics are awesome while the MS one's are even awesomer. Chords are easier to play on the MS but not by a massive amount. It's more about the consistency of the sound, string-to-string, and the tension being manageable on the high side.
The new model is a massive step up in the aesthetics department, but that was an easy challenge as
I really hate the brown finish of the old one as much as I love playing it.
Another thing I really dig is that the new multi scale feature allows for a much better intonation. On the old model, my low and high E bridge saddles are maxed out each on the opposite side, and it is barely enough for the high E to intonate correctly. With the new model, no issue at all.
So, just for the intonation and aesthetics, I'm gonna keep the new SRC6MS and sell the old SRC6. If you have no issue at all with the old model, the upgrade may not be necessary.