As is typical of the type of individual who chooses to contribute to any single marque forum (myself included), we do tend to exaggerate the differences between the various models and versions and the importance of some of the minutiae and subtle revisions can be amplified disproportionately. In the real world, which still exists outside of our little fanboy/forum/owners club bubble, non of the above applies.
We talk about the visual differences between a 3200 and 4200 as if they were chalk and cheese when in reality, it would be reasonable for any neutral, normal, well balanced individual to say that they were almost identical to each other. I cannot think of any other current or historic example in a potential car purchase where the design of a rear light cluster, pretty as it is, would be fundamental to the decision making process. Park a 32 and 42 backed up against a wall and 98% of the population would just see two Maseratis.
Mechanically they are indeed chalk and cheese but do exactly the same job but in technically different ways. Some will prefer the lag, spool and boost characteristics together with the warm comfort of the knowledge that there is direct lineage to previous (real) Maseratis. Some will want a typical N/A linear delivery and the warm comfort of the knowledge that the technical expertise and deep pockets of Ferrari were involved.
On a limited budget with a fixed ceiling, I would have considered either engine, any transmission and pretty much any colour as I was determined to buy purely on condition and history, which I did. With endless funds, I concede that the buying process may be done differently but is irrelevant in my case.
I now own a Maserati. I do not expect it to make money. I do not miss having boomerangs. It has bit me on the **** already in terms of running costs. I love it.
In terms of future values it is true that the first of the breed, with some exceptions, tend to become the sought after models some years down the line. This does not necessarily mean they are a better machine for the driver, it means they have a more attractive chassis number to the investor.
To play devils advocate, I will suggest that the 4200 will hold it value just as well as a 3200. My theory is that at some time soon, there will be a rose-tinted desire to own a raw N/A V8 performance car in a world filled with default environmentally friendly sequential twin turbo contemporary sportscars. This theory may also mean that a 4200 with a gear stick may become the holy grail in our flappy-paddle future. I will await the flaming.
There will always be safe bets, such as an Assetto Corsa but otherwise it will all boil down to how many survive. It has already been demonstrated that our 32s and 42s are probably worth more in parts, than as as a whole. It is also probably true to say that they are not a viable ownership proposition outside our fanboy bubble, as used values will testify.
Depreciation, in isolation is meaningless. These are old cars now and it is whole life costs during our ownership that is important. Our collective Achilles heel is of course maintenance and running costs which are preposterous in terms of the relative value of the car in my case. I do find this unpalatable but illogically acceptable as do you, or you wouldn't be here.
Find one that appeals to you, drive it and buy it if you like it. Do not expect it to be a good investment. Expect it to cost you money. If you are not a naturally optimistic positive thinker with a contingency fund, then best walk away.
Oh, and don't get hung up on light clusters!