I'm shooting architecture/interiors with the SK35 + P45, and I often end up in situations with areas of strongly coloured/mixed light (e.g. a tungsten interior with a window with bright daylight streaming in). After looking at a few threads here and on forum.phaseone, some people have argued for exposing your LCC plate with a consistently coloured light source -- for instance, firing a speedlight at low power at your LCC plate for your LCC exposure. I've been trying both exposing an LCC "conventionally" using room light and exposing an LCC with a speedlight, and I'm noticing that there are a few subtle differences--particularly, the corners seem to get a bit brighter on the speedlight-exposed LCC, and colour casts on white areas seem more technically accurate but possibly less pleasing.
Are there any good rules of thumb for what's likely to produce the best results?