Are your portraits actually overlapping the health bars (and being transparent enough to see the health bars behind them, I assume)?
If so: GREAT! idea!!
I tried this, and I couldn't see the combat text. Which made it tough since I use stopcasting a lot to decrease my overheal and I let my heal stop or let go depending if the tank parries/block/dodges =P I can probably move the combat text but decided to just take out the portraits altogether again.