Well I kept going and finished swoon block 1 (er, about 3 weeks ago).
I like it, but I am not sure it is how I want my swoon quilt to look. Can't decide whether to bring in some really different fabrics to make sure there is a big contrast or to keep going with my original pairings.
I'm leaning towards the first option (which is making me very glad that I bought 5 metres of the background fabric "just in case I make a mistake" - I wan't anticipating it being "just in case your first block is a mistake"!).