Yeah its heavy but I'm used to it. I've been playing 47-48" drivers for awhile and started experimenting with heavier drivers this year due to my success with my m1 3 wood. It is the first 3 wood I have been comfortable with so I built my M1 driver to the exact same specs (same weight, same shaft and same length). I have since increased the length to 45" and am liking the results. Of course I also have 3 weights in the head that I am moving around so that might be influencing everything as well.
Overall, it feels fine, equivalent to a 3 wood that's been extended a couple of inches. Its not that heavy really but I am used to it and prefer a heavy feel with all my clubs - maybe being in my mid 40's I have developed some good "old man strength" !