So I got the 2 rolls back today.
First - if I'm going to shoot colour seriously I'll need to find a proper professional lab. I've not shot any colour negs for a few years. This joint used to do reasonably OK work, but I don't think they've dusted their machine in the last couple of years - a bazillion dust spots on the prints.
Next - the film's definately 400 - it's right there on the rebate. BUT - the roll I shot at 320 is a bit thin, while the one at 160 actually looks much better. The prints don't look overexposed either - no blown highlights. I've uploaded one to the gallery. If I find any more of this stuff in the freezer I probaly will split the difference and shoot at 200.