Barring the fact the cx450 is far better quality, has a 40c full output rating (the cxm430 is only rated at 30c), & a 5 year warranty they are based on entirely different platforms regarding ac to dc conversion.
The cx430 is group regulated , meaning 3.3/5/12v conversion is split at source.
The cx430 has a max 12v capacity of 384w at 30c temps
The cx450 is DC to DC regulated.
Meaning AC mains voltage is converted solely to 12 v then the 3.3/5v is filtered off the already converted 12v as required.
This means in theory the 12v is able to supply near enough the rull rated capacity of the psu (448.5w according to corsairs specs)
The average system with a couple of hard drives, optical & a USB keyboard & mouse would need 15-25w of that realistically so youre down to 425-430w or so realistically.
That's 50w more capacity than the old cx430 worst case scenario.
You could run upto a 250w gpu & a 100w cpu on the cx450 no issue at all if necessary.
& yes a 550w would give you more headroom - but you're not doing that for $40.
The aerocools ??
The kcas has 444w 12v & is poor quality.
The integrator has an extra 12v over that , no bronze rating & is godawful quality.
Steer clear of the aercool units completely.