I have been playing with both setups and have come to prefer the A1 faith merc.
I was at about 7.3k damage with the might/pride merc, but he has a habit of getting dead alot on chaos and baal runs, reducing damage back down to 4k on a 3 frame strafe
The faith merc keeps me at 4k damage but much faster rate of fire. I did 9 chaos runs last night and merc nerver died. My old A2 merc might make it thru 1 run alive by some miracle, but never 2. The windforce's knock back at the fastest strafe speed is amazing at crowd control. Still a decent killer even in 8 player games
I dont know how to actually compare the damage outputs of each setup to compare power vs speed. My point mainly is that A1 merc seems to like to stay alive alot more than an A2 one. A2 auras are very powerful, but cant be relied upon to be there as much.
-one other advantage of a1 faith is freeing up gear and still being able to reach best ias break point -- you can dramatically improve damage on with an atma's scarab ammy - has ctc amp on it. Great for breaking phys immunes too.