RdsOn isn't so important for linear applications. That's an impressive part, but our TO-247 with lead frame has more thermal mass. It can handle about 3x more heat in 20us, which is important. The TO-247 is also easier to get heat into a 100W heatsink, needed for long pulses or high rep rates. Some other TO-247 or SOT-227 parts might be better. My linear circuit would also be happy with multiple MOSFETs and mR source resistors, drains in parallel.
Yep, I have a nice stock of big parts like that. Our 5 to 20mR values are chosen with high voltage drops in mind, needed by the circuit. (E.g., 4V compares to Vgs=4V, 1V for opamp control.) Small size, low inductance is necessary for fast di/dt. The Ohmite FCSL110 wide 5W sense resistors also come down to 1mR, and in an FCSL150 10W version. They're better suited for small circuit boards.