422 and 444 cameras - buying advice please

Hello all, thought I'd ask for any suggestions people may have for cameras.

We're currently shooting on high end HDV (ha, high end), but we're pretty much exhausted the possibilities HDV offers, and just need more detail in the colours we're recording.

We're shooting models on white backgrounds in a well lit studio. We colour match the outfits to retouched stills - what we shoot must look as close as possible to the still coming to life.
For the most part this is just about ok on what we're using at the moment (a Sony HVR 270) but there's not enough detail in whites and extremely saturated colours.

So, assuming a budget of up to around £20k (a bit more in US$, but remember we get massive import duty on electronics so it's close to a 1:1 conversion), what do we want to look at?
I've a few ideas already, but won't bias the discussion with my thoughts just yet.

Many thanks in advance!