My SC600w Mk IV Plus showed up last night. I am mostly comparing to my previous EDC the Zebralight SC600 Mk II (not L, just II). The tint shift is barely noticeable on the plus. I doubt a non-flashaholic would even seen it if you asked them about it. The tint shift is much better than the Mk II. I am very happy with the tint, and the tiny amount of tint shift (almost none). I will post more thought in the official Zebralight thread.
As for low, yes this does not go as low as the Mk II. The Mk II lists 0.6, 0.1, and 0.02 for low. The Plus lists 5.0, 1.8, 0.6, and 0.2. First are the Mk II numbers wrong? I can only eyeball it, but the Mk II 0.02 is much lower than the 0.2 plus. And even the Mk II 0.1 is a bit lower than the Plus 0.2. So they may be relatively close to the right numbers.
So even with one more low level, the Mk II still has two low levels that go lower. The difference is rather significant. But for my real world use it won't be a big deal. I only used the lowest low on the Mk II when I wanted to preserve my night vision. I do feel that the Plus 5.0 low is so bright it feels like it should be in with mediums.