If they have a higher flow rate they will obviously over fuel, but won't be as dangerous as running lean, the LIGHT blues are good for 350-390, what is the part number of the dark blues, I'll look it up for you.
Why not just keep things as they are all nice and correct, till you have everything ready then swap things over ?
Just because they may flow more fuel does NOT guarantee more power, it will still lose power over a better afr if too rich, and belch black soot!!
I can't see there being a difference in spray pattern, between the two, unless one is fitted to some oddball engine as std.
tabetha