I saw the 400 at Cranfield 2-3 years ago.
It looked very nice, inside and out. The interior was nicely done up. Similar kind of stuff to a Malibu, etc. It was owned by some businessman and he had a hired pilot flying him around Europe.
Yes the -480 water-cooled engine was a market failure, but I have not heard of reliability issues with it. Lyco are OK supporting their old engines; they still support the IO-720 which was used in how many airframes? 1 or 2 at most. Mind you, the IO-720 probably has mostly the same parts as an IO-540, just 2 more cylinders...
The 500 is flying; I believe there are a few prototypes around, doing the rounds of exhibitions and airports here and there - I got
this pic at Losinj LDLO last summer. Have they actually sold any yet? It has great range with full tanks, albeit being only a 2-seater (with luggage) then.