The conditions for test casting the Slick Stream were not ideal. Spring has sprung but whoever decided Spring starts on the 1st of March rather than the vernal equinox doesn't live in Scotland, so, having found a moment of drizzle between snow showers...
The Slick Stream is a limp line, even in cold conditions it has little coil memory, what it has casts out easily. Coil memory has become something of an obsession with UK fly fishers so that should suit UK anglers well.
The coating is very smooth, not oily.
I'm told the first 30ft of this line comply with AFTMA specs for a #7 line, casting it feels normal to me. I'm told the reason for giving a dual rating is when the full head is in the air it's more like an #8 line. This is all double-dutch really.

This is a WF7 line by definition, as with any line the weight increases with length - duh! Depending on your way of thinking (and marketing jargon) the Slick Stream either has a long front taper (3.25m) or a long convex front taper or a stepped belly or a step tapered belly. Take you pick! It's a neat trick, that long taper holds the first 30ft to ATFMA #7 weight and it's followed by a thicker 7.15m main belly.

I'm tempted to say this throws a neat loop but loops are decided by casters more than rods or lines. Turnover is clean and positive. The tip seems relatively fine to me so presentation at short distance was precise and crisp. At long range the Slick Stream does extend fully and turned over my leaders fairly consistently.

Since this is a #7 line I don't really get too caught up with short range casting, I expect to be throwing some distance, at least the full head, if I'm using lines of this weight. The Slick Stream deals with all the fishing distances I need and more. On a damp day, casting against the tape, I maxed out at 110ft. Throwing to 100ft was consistent and relatively effortless - by that I mean no Arden ballet steps - both feet firmly on the ground, one or two false casts and shoot.
This is a shooters line. I consistently found myself carrying 55ft to 60ft and shooting the rest. Carrying beyond 60ft felt both awkward, time consuming and rather pointless given the distances I achieved with shoot.

The hauling zone.
To my mind, the idea behind the hauling zone picks up the notion of anglers marking their lines at the point where the head suits them and their rods. We have a similar point of reference on lines with contrasting running line and head colours. (eg. Cortland, Snowbee, Rio etc.)
In use, I must say that orange section proved useful, strip back the running line and lift; quicker and more positive than any single-coloured WF line. Depending on rod length I found myself varying the position at which I picked up the head: for 9ft rods the orange section was in my hand; 9ft 6in it was in the rings: 10ft it was just touching the tip ring. The hauling zone gives the caster useful points of reference.

I used a prototype of this line last year during a Norwegian salmon trip. The head weight seems to suit hauled switch and roll casts. I certainly had no trouble consistently covering the water I aimed at - caught some fish too. For much of that time I fished with sinking Poly-leaders. The Slick Stream did turn them over well enough but if that were to be the main job for that line I'd probably chop off the level tip. My guess is the tip is slightly light (thin) for the leaders I used so cutting back would smooth any tendency for tips to kick.

A very good general purpose line.

Technical stuff
Length: 30m
Head length: 13.7m
Head Weight: 19.75g
Colour: White with a 1.25m orange "Hauling zone" set 2m from the end of the rear taper.
The diameter of the tip and running line is slightly less than .9mm and the head is about 1.45mm. (Line diameters are approximate since line coatings compress which confuses my calliper!)

Details of #7 lines for comparison:
Head lengths (published head weights)
GPX 12.8m;
XXD 20.5m
555 13.7m
444 Precision 12.8m
Windcutter 12.8m
Accelerator 14.6m (326gr = 21g)
Snowbee XS 12.95m

For test casting I used half a dozen rods (Hardy, Greys, Orvis, Sshoot, Scierra, Loomis, Bloke), 9ft, 9ft 6in and 10ft, all rated #7 all with ERN values higher than #7 - typically 8.5. To the CCS ignorant that simply means the rods I used are typical modern 7-weights.

Details from www.sshoot.com