D3 and D2 are quite similar. Main difference is, you can afford to get into battle and you can recruit farther (although, I think you can successfully recruit nationally in D3).
One thing to note, there aren't much differences between low end D1 dropdowns and D2 recruits. They are all around 460-520 in rating, so I would go for more towards potential. If a D2 recruit potential is good, grab him rather than a 520 rated D1 recruit with mediocre potential.
And a word of caution. In d3, you can win battles against D2 teams. In D2, you will not win any battles against D1 teams.