As with any information, you need to consider the source. It's important to read many/most of the reviews on a particular site, to get a feel for the style. For example, while I find Bryan's reviews very reliable, it's important to note that his reviews are generally positive and upbeat - he usually finds something to praise about every lens (which is not unreasonable, but helpful to know if you're just reading one review). One of the very nice features of TDP is that in addition to the text reviews of the lenses, there are technical comparisons of sharpness, vignetting, distortion, etc., showing the actual images (as opposed to reduced and plotted data), which allows the readers to see for themselves and draw their own objective conclusions.
Each reviewer has his own style. However, several that I've now read have a lot of positives and few negatives. I have a 1D MK IV which I bought to replace my D800, however, I've yet to use the f/8 AF capability. I never used it on the D800 either.
If you are one who cannot afford those big whites, or just like me, can't handle the weight, then using a 400mm f/5.6 or 100-400mm with TC is a advantage over using a 7D. and no TC.
I need to try my MK IV at f/11. My 1D MK III would AF at f/11 with certain lenses.