The person not liking a VH2 and then disliking the VHX is not surprising. Diezels have a unique tonal and feel signature that you find across all their amps. Some are a bit tighter, brighter, looser, etc but the overall tonality and feel is similar. Absolutely I encourage trying before buying, although I get that high end amps like this aren't always easy to find.
As for the VHX, as I said, it is a top notch, incredibly versatile piece of kit. For someone whose "Diezel tone" is all about the VH4 or Herbert.....maybe a VHX is excessive and they may as well stick to the namesake amp. But for those who want one Diezel that can accurately capture what the other Diezels are about, it is hard to beat a VHX.