Mine were both strung with the same strings (D'Addaro XL nickel rounds) but I hadn't had a chance to play it at volume when I posted that. Now that I have had a chance to turn up I think the 2015 is in fact darker than the EB5 in the lower registers (not including the B string, that's a whole different world of dark) and the TBird is capable of going a bit brighter than the EB as well.
I had a new set of DR Hellbourg round nickel strings laying around, so I slapped them on the 2015. Interesting strings, never seen or played anything like them in the past. They have a huge diameter outer wrap coil that looks like it would feel very rough and bumpy and have lots of unwanted finger noise. Here's a snap shot of the E and A string installed next to the XL wound rounds on the G and D strings....
View attachment 3361438
Actually, the strings, although somewhat bumpy feeling have very little finger noise on slides and fretting. They're actually quite nice sounding and feeling. I was able to drop my action a bit more with them as well. Now down to 1/16" air gap between the 12th fret and the bottom of the E string. I need more playing time with them to draw any strong conclusions but for now they're interesting and seem worth a try.
The good news is, I don't have that move in my routine.
There's nothing inherently unstable about the VP neck. Mine is rock solid. That said, temperature and humidity changes can effect any bass neck. Obviously, if you have your bass near a window (especially an open one) or in direct sunlight or near an HVAC vent it will see significant temperature and humidity changes resulting in necessary neck adjustments. Other than that it's not unheard of for a neck to take a day or two to set in after seeing extreme temperature and humidity changes.