Board specs should show the effective edge or contact length. For example, Lib Tech shows the contact length on their specs. A blunted TRice 157 has a contact length of 121 while the 157 skunk ape has 117 and the 161 skunk ape has 121....so it may be correct to assume the 157 TRice carves similar to the skink ape, all other things being equal.
However, I don't know if other things like flex are also affected by the board size...i.e. a smaller length will feel softer even though the contact length is the same
Good point. My previous comment is with the caveat "all others things being equal" and that is almost never true.
Here's my basic gross simplification
Long board length, short effective edge (like my Never Summer Summit) will turn on the snow like a much shorter board, the big nose will blast through cruddy snow and float well in powder. Drawback is higher swing weight (so spins over 360 are going to be harder... note I specifically say spins OVER 360... if someone talks about swing weight for just a 180... then they are not very good park riders and are doing them wrong).
Shorter board length, long effective edge... low swing weight (easier spins), but still have more control and stability at speed and on steep. Drawback is that the board will not ride over cruddy snow as easily (longer nose soaks up the shock a bit) and also will be more likely to submarine into deep powder.