The RX-V430 is not one of Yamaha's higher-end receivers, so the 1070 is likely to offer better amplification (clearer sound, more dynamic) - it may be rated at 10W lower, but it's rated much more conservatively. I upgraded from a Yamaha receiver to the Model 1050 almost six years ago (how time flies) and even though the rated power output dropped by something like 15W or 20W I noticed a definite improvement in power. The DAC's and processing are both likely to be an audible improvement for TV/movies and for music.
If you only have a 5.1 speaker setup, the addition of 6.1/7.1 surround modes (Pro Logic IIx, Dolby EX, DTS ES, DTS NEO:6) won't be much of a factor, but you would have the option to try a 6.1 or 7.1 speaker setup with the 1070 and those modes.