there would need to be a relatively easy way for players to see/calculate jump times, though
I believe it's important only when you're planing your route for a contract, and the advanced navigational array gives the total travel time. I was maybe slightly ambiguous, when I talk about "mass" I actually think about cargo bay size. Although it doesn't have to be exactly that.
How would the game cope with ships sharing a wormhole?
Good point! So actually it's more a property of the wormhole and it's generator. A player who wants to follow through would have to guess the timing by the size of the ship, but the wormhole scanner could display it.
Are there other gotchas? Like a core or Random Hits mission implicitly expecting a certain jump time? Hmmm... Maybe RSS missions could be a problem.
Yet, I have a big ship, and I deliver goods, on time or I ain't paid. What would you do of me and my associates, pal?
I guess you worry about cargo contracts? The deadline calculations would certainly have to be revised to take the longer travel times in consideration. The other contracts shouldn't be changed. Which makes it harder to fulfill them for big ships. It's only fair; small ships don't have access to cargo contracts
The bigger a ship the more fuel would be required to keep the same speed or jump the same distance.
Actually, fuel is more expensive for bigger ships already. Nobody notices because fuel is as cheap as water.
gigantic ships like Andromeda would need years for a simple jump
Actually I was thinking about a logarithmic formula (here is a helper if your maths are a bit rusty
), so very big ships wouldn't be harshly penalized. This is necessary anyway just because of the Conda and its 750TC if we consider only the core ships.
But it could be a key in the ship properties, so ship builders could adjust it to what feels right to them.
So the formula would be Time= (k*Distance)^2, with k being the ship's constant (k<1 for small ships, k>1 for large ships, k=1 for the Cobra III). k being based on the log of "ship size" could be either a rule of thumb for makers or computed by the game.