the intermediate line i use sinks pretty quick, although it needs a couple of tugs on the first cast to get it down, i'm going to derwent next weekend, i'll have to get me boobies out!
I own a Snowbee XS clear intermediate (also known as slime line) 8wt and it shoots out like a dream, find it easier to cast into the wind than my floater with it being more dense.
I would highly recommend it, never had a problem with it floating either, like some intermediates do, try greasing the line before you first use it and every so often. It has to get through the surface film and sometimes sticks up there a bit until it gets through it naturally.
If, on the other hand you de-grease the line it will cut through the meniscus and sink more readily.