It's subjective in the end, but the 3 PRO makes the 410hlf come alive. I owned two 410hlf's and hated both of them with other heads. The 3 PRO makes the 410hlf sound fantastic - low end is large sounding, midrange punch is ACTUALLY PRESENT, and the high end is clear and very much there. When you crank the tube gain on the 3 PRO, it sounds awesome through the 410hlf.
The 4 PRO is still a good head, I just do not like the main tone it puts out and constantly tried to dial out the massive low push at 150hz and lower.