The 421C is pressurised.
Of course a KA will be better in many ways (I see them a lot, as I share a hangar with a load of turboprops) but the 421C has a FL250+ ceiling, deice, radar, this one had a heated front screen (loads of £££), so I don't see where a first order difference in weather penetration capability would come from.
this one had a heated front screen (loads of £££)
Thanks for reminding me of the cost...
Regarding C421 vs KA.
If I'm not mistaken, the 421 has a reputation of being the most comfortable and quiet piston twin ever produced. But of course a piston can't compare with a turboprop. That's probably why the KA is still in production while all the heavy piston twins are not.
There can be mission profiles where it makes more sense to buy a 421 than a KA. You get them almost for free and you can buy a lot of AVGAS and can overhaul a lot of engines for the difference in price.
If cost is your key determinant of mission profile then of course. There are other factors that could (or should I say would) favour the KA.
The 421C is pressurised.
I know that, I have flown in one, but the system is reputedly rather less reliable than the King Air's system.
To me the main benefit of the KA is the knowledge that you'll be able to go, because it won't be in the maintenence hangar when you need to use it. They may be old fashioned, but they are reliable.
To me you get an extra layer of safety because of the two turbine engines which are inherently very reliable; I know they can fail but do so much less than turbocharged piston engines.
For me, turbines at low altitudes are wrong, and so are piston engines at the levels needing pressurisation.
In any case all of this discussion is irrelevant when for the price of a C421 plus the upgrades necessary to get to the sort of concours standards you have mentioned before, you could get a Citation. That's the real deal, and it's only the ability to operate into shorter and grass airfields that keep the King Air going.
You get them almost for free and you can buy a lot of AVGAS and can overhaul a lot of engines for the difference in price.
A run out 421 (which will cost you another 100 - 200 k € the first two years of operation) can be had for little money. A good well maintained 421 goes for around €300k.
Many of those "good deals" on twins in today’s market are twins that will need lot of attention and money before you get them up to snuff.
Sure, Neil, all agreed, but on that basis I should throw away my TB20 and buy a TBM 
I personally don't really like flying old wreckage which is one reason why I bought a new plane in 2002, but one can make a case for buying a plane of any given age or condition, depending on one's capital v. income situation, and also according to other stuff like the mission profile.
If you have a million or two, you can buy a functioning used KA, and if you don't need the short field performance you can buy a jet. Jets are going really cheap nowadays; you can get a really good one for the cost of a new TBM850. But they can't do the short runways which are all over Europe.
The reality is that most people in piston GA cannot afford a turboprop - not even a Jetprop which costs $1M for a good used specimen. But some can afford a shagged twin for say $150k.
I think what stops a lot of people flying twins is mostly the fuel burn, but also the associated hassle of annual revalidations, and the higher cost of getting a ME PPL/IR in the first place.
The other thing is that a twin TP, or a jet, falls under "EASA Complex" so while you can run it under Part 91, you will also need an EASA signoff. I don't know if this has been defined yet but this could be a hard hit for some. An EASA CAMO has no competence to sign a release to service on a non EASA reg plane, so depending on how the AMCs are finally drafted they might do anything from "nothing but a signature, Sir, for £5000" all the way to recertifying 337 field approved mods (which would be a nightmare). So I predict a significant migration to SE TPs once this sinks in, which it hasn't yet. One assumes EASA defined "Complex" thus to stick a finger up to the USA while protecting Socata and Pilatus.
Peter a good used Meridian (or Jetprop - not sure why you only ever mention Jetprops) is well under $1mn now.
I said "good used".
It's worth doing some pre-buy due diligence on the airframes and what mods were done in what years.
