One thing you could try with the Dumbbell rows to make them feel heavier and to hit that spot that the Straightarms are hitting (the upper lat) Is start with the dumbbell under the bench (as if it is under the opposite pec to the arm that you are using) and pull them out and up rather than just up. I have done them this way before (admitedly it was with a guy who believes in targetting every bit of every muscle), but it definitely made me ache in a different way AND i couldnt use as much weight.
Just a thought buddy
TEAM CROM (supporter) !!!!