Certainly no bullets have come along which will be an improvement over the one Keith designed for the 44 mag, bullet number 421429. I don't think there is any powder on the market today, which will improve Keith's original full power load for the 44 mag with that bullet, 22 grains of 2400.
Some on here will say that H110, a powder that has been around for some 65 years, is an improvement, but testing will prove that 2400 is still the best.