First, I'd want both to be series II units: tad more beef with slightly better specs (and I tend to like giving the engineers another crack at things). Then, between the two, I'd go with the 3-channel over the stereo unit simply because it "comes with" its own spare parts (3rd channel) in case you lose the L or R in your setup. Plus, I'd actually go in and pull power to idle the third channel of the 1430 until and unless it was needed. Good luck.
UPDATE:
Actually, looking closer at the construction of the two amps, I'd go with the 125.2 stereo unit as it appears to have much better construction than the earlier 1430. I'd still like to have the spare parts on hand, but not at the cost of difference in engineering and quality construction between the two generations.