Stepper driver suggestion

We're doing a CNC conversion and we've had a few issues. We've got a breakout board from cnc4pc which seems like it works well and two nema 34 stepper motors that want 4.24A when wired bipolar parallel. For a stepper driver we opted for a MA860H since that's what Tormach uses for the A axis in our 770 mill. The MA860H has been a complete disaster. The first two were DOA. Of the next two, one was DOA and one would only spin the motor one direction. We know this unit can drive this motor since we hooked it up to the driver in our Tormach and it works perfectly. It just seems to MA860H is shoddily made and the "QC passed" stickers are meant to be ironic.

Now we're looking for alternative stepper drivers and I'm hoping for suggestions. The KL-6050 looks like it might fit the bill as does the KL8060 DSP-based controller. Both are less expensive which is attractive, but appear similar to the MA860H in terms of quality. The Gecko drivers such as the G213V look interesting at a higher price point but require an external heat sink at the amperage we're looking at.

Does anyone have experience with either the KL or Gecko drivers, good or bad? Can anyone recommend a reputable web site for buying them? The web site with the attractive KL pricing also sold us a CNC4PC breakout board that is rev 1.5 when the current rev is 8.1. (You don't know who the original source is until you receive it.)