Extending the list of purchasable units to different levels of light and heavy or elite status could serve to bog the game down a bit and just make it more complicated. I mean after all, few people have the resources to buy OOB battleships or the desire to buy cruisers, let alone all of these variants. This also may be my preference for using a 6-sided die; there are only so many numbers to use. It does limit the differences in unit types.
But maybe that is just me… My intent has always been to use whatever units HBG makes as doubles for the OOB, mostly regardless of their wartime status. So a Nevada-class battleship would be like a normal battleship 4-4-20. An I-16 would be the same as a Yak 3 and so on.
However, in looking at your chart for ships, I will say that I do like it. Ships are one area where I can really see this working (as opposed to fighters or even tanks). I would like to see heavy battleships and heavy carriers as purchasable unit types.
The real challenge will be for some less historically minded people in identification of what class of ships are on the board. It is easy to tell the difference between a battleship and an aircraft carrier, but what about a light cruiser and a heavy cruiser? A light cruiser and a destroyer? A battlecruiser and a cruiser or a battleship? Really I am not so worried about that, if anything the confusion should be entertaining.
Or, what if there are two different sculpts for essentially the same unit type? For example: what if (and very likely) HBG produces two light carrier designs for the US or Japan (or what if one is called and escort carrier and the other a light carrier)? Will you try to differentiate them or use them interchangeably as a light carrier?
A simple solution is the best solution. But at least we have variety.