Sounds like a classic case of twofootitus :mrgreen:
I really liked the 2120 I owned, but the deck area was always tight. Two foot more would of been a big help for me.The transom was not an issue for me, I removed the splashwell and liked the added foot room.
How much that two foot would cost you in a trade is a major issue. Your likely to get hammered pretty hard by the cost.(and the wife!) Kids grow quick, I would not do it.
Now if you really want to upgrade consider a 2520 Lots of more room for a growing family in one of those.
Just like cars boats value drop quick when you leave the lot. To limit that hit you can trade into a used 2320 but still the move will cost you.