The beamshots that I took came out terrible quality. In their stead, I will post my observation on beam performance of TN42vn versus K70vn:
Of course, the webosphere is chock full of stock TN42 versus stock K70 videos and beamshots, but I only have the Vinh54 versions.
Here goes: The less initiated the observer, the less of a difference between these two lights' beam performance. The more experienced the observer, the more differences can be seen in the beams.
Close range: TN42 has a tighter, narrower beam, with more brightness in the center of the beam. But, this is not the range that these lights are intended to be used at.
Medium range: Same as above, but a little harder to grossly observe. This range is near the intended range use for these lights. But not quite.
Long range: Now we are at the intended range that these lights are designed to be use for. At this range, the TN42vn visibly has some more light on the target; the target is some more better defined. How much more? Appears to be about 10% more, kind of, sort of, approximately.
Buy the newer light if you already have the older light? That depends on if your want/need for some more performance is less, or more, than your hesitation to acquire and keep another light.
Or put the other way: That depends on if you desire to acquire and keep another light is equal to or more than your hesitation about the "some" more performance.
By the way, both lights squarely focused on the same distant target: Notably brighter target. Ganging two or three of these such lights would yield spectacular performance increase.
B by the way: As usual, I am more interested in my observation of beam performance when comparing different lights; people have different opinions on the physical light itself, such as switch, UI, etc.; so my opinions on such matters are of less importance than my observation of beam performance.