This is an interesting question fraught with legal, and ethical issues. Perhaps an ink blot test for DIYers, revealing personal motivations.
Important questions (IMO) are not as much the individual's personal intent, but how using somebody else's mark is interpreted by others.
While some may rationalize this as a honest homage to a classic product, it is hard to escape that the "good will" of that classic product is being shared by that counterfeit (I know, an emotionally charged word). If effort is made to resemble the look of the original mark, how could this not confuse what the association is?
Another question, what is the extent of "good will" associated with a classic product? Is it limited to schematic and the values of parts used? Or does it encompass, component quality, build quality, PCB layout design (a factor for better or worse in performance), control ergonomics (placement and laws), etc?
More questions than answers. In commerce it seems pretty clear cut (don't do it). For personal use, if you are the only person to ever see it, you are not likely to confuse yourself. When showing off such gear to third parties, it's hard to imagine that there is not some dilution of the "love" enjoyed by that old mark. Whether this helps or hurts an individual's reputation, depends on the mindset of the viewer. I am probably not typical in this regard.
Sorry, I'm sure my personal biases are showing. Being copied by Uli is not the honorarium that being copied here is. I have openly shared all my kit designs, since that was the deal I made with my customers. Commercial designs and work for hire are a different matter. Of course what you do in the privacy of your home is your own business, as long as you don't break any laws of man or nature, and/or don't get caught.
JR