Thanks for the responses guys
I've already applied a few coats of gloss, and the "streaking" only become apparent after the first gloss coat had dried.
It's not worth the trade-off of diluting the metallic blue paint as I noticed a significant change in the way it caught the light when I tested the paint.
I've let a few friends judge the finished figure and the unanimous decision is that it's not to be messed with. To notice any flaws in the toy you'd have to holding it in direct and powerful artificial light (like a camera flash), and viewing it from less than a foot away. Any other time it looks spectacular, mainly because of the way the blue catches the light. Normally I would have applied thinner coats to reduce streaking, because I learnt from Jin's guide (and I'm flattered by Meverix's comment).
The weapons are either Actionman, GIJoe or something of that scale.