You number are seem to be abit off, this is dps of tommies are according to firespaks:
2 brens+2 enf 18.2 19.0 19.6 20.2 20.8 21.5 21.8 21.6
4 Endfields 19.1 18.4 17.1 15.9 14.9 13.9 12.7 11.6
2 Brens according to firesparks give 10 DPS not 8.
Hm, stats.hu on the other hand says brens(tommy brens) DPS is 6.34 while timmy lees are 3.08 far, which means 4x lees is ~12 while with dual brens+lees its ~18,8 which gives us ~6-7 dps difference.
I admit though, my first numbers were out of memory for brens.