So I got the Rode VXLR+ recently and I must say I am not happy with it. I could have known, did I dig deeper in this thread before ordering it. As others pointed out, the Rode VXLR+ on the MOTU is introducing a ridiculous high noise floor.
In my setup (MOTU M4, Rode VXLR+, V-Moda Crossfade M100 Master + V-Moda Boom Mic and TRRS to 2xTRS split cable) I got really noticable noise floor at around the 12 o'clock position with input gain, But since that was not enough to get a high enough input level for the V-Moda Boom Mic, I had to rise gain to about 2-3 o'clock position and it sounded like I was recording in pouring rain.
As others have mentioned also, the fun part is: If you only plug in the Rode VXLR+ and plug in no Mic to it, as soon as you enable P48, the noise floor is there. So it is not introduced by the Microphone.
I wanted to do one last test bevore getting rid of everything, so I ordered the insanely expensive Rode VXLR Pro and oh wonder. No noise floor. I can crank up the input gain until everything clips badly and I can not hear any noise floor.
Yup, the MOTUs seem to be incompatible with the general "cheaper" XLR to TRS adapters for some odd reason. So if you plan to use TRS microphones, be prepared to spend quite a bit more money on your setup.
Although pretty expensive, I will keep everything how it is now, because I am very happy with the sound quality, build quality and the handling / function. Also the drivers seem to be very stable and I had zero issues getting the unit working on my Windows 10 PC.
Oh, and to this day no response from MOTU, the local Distributor nor the shop where I bought it about the 3.6 V Output on the TRS part of the XLR/TRS part. It is obviously wrong in the manual now that I studied the manuals and tech specs of other similar devices, but I wonder why it is so difficult to get an answer. I hope things work out OK if the unit gets a problem while in warranty and people communicate.