I have the pro 4 and I don't like the stx blade. I'm actually removing the two teeth around the point to prevent freeze up. I also don't like the weight. The Pro44 looks to be lighter 5lbs or so and it doesn't have the stx blade. That said I would try the pro44.
Personally if I were in the market for a new auger I would get an ION 10" (for weight), Eskimo Z51 10", or maybe a strikemaster honda 4 stroke, but with a 10" chipper bit. chipper bits are slower to cut but more durable in the shallow water fishing I do.