for me 430 any day!
initially when i bought it it took me a while to adjust from the 400 - the 430 is marginally noisier in terms of cabin noise and not as smooth however the extra easily compensate for that - if i had enough disposable income i would have an immaculate example of each mark !
p.s in over 3 years of ownership i have only had a parking sensor go, door speakers blown - cost £12 to repair and amplifier packed up costing £300 to repair