In general, the DHs take a big chunk out of the budget - having to pay for 1 more hitter and 30-40 more IP. Unless the DH league is the 60M or 120M league, it always creates a big gap in player quality between one league and the next most expensive one.
And the one player per year rule is good. Gives you one more thing to think about when drafting each position. "This player is really good, but can I afford to burn this year already?"