The scalability of semiconductor diode lasers to multi-kilowatt power levels has increasing importance in direct diode material processing applications. These applications require hard-pulse on-off cycling capability and high brightness achieved using low fill-factor (FF) bars with a tight vertical pitch. Coherent uses 20%FF bars operated at <60W/bar packaged on water-cooled packages with a 1.65mm vertical pitch in the Highlight D-series, which achieves <8kW of power in a < 1mm x 8mm beam line at a working distance of ~ 280mm. We compare thermal measurement results to thermal fluid flow simulations to show the emitters are cooled to low junction temperatures with minimal thermal crosstalk, similar to single emitter packaging. Good thermal performance allows for scaling to operation at higher power and brightness. We present accelerated life-testing results in both CW and hard-pulse on-off cycling conditions.