Hi
thinking about getting a Duotone wing, 6m or 6.5m. the original slick is on offer, so is there a huge difference between the two wings. is it worth the extra $$$ for the latest version. thanks

I would not use an OG slick if you paid me. I had my old 4.5 in my car today and my 4m unit was in the shop. I opted to be overpowered on my 5.5 unit rather than ride it.
I'm going to use it to learn backflips when the mood strikes and put tons of holes in it.

They suck at tacking, backwind in any gust. what else?
New slick sls is a dream. I have a 3.0. It's just like the units in many ways.
The other thing is the latest gen of duotones don't seem to bag out nearly as quickly as the OG slick.

From my limited experience: original Slick has better low end compare to SLS. It also has smaller wingspan. So for large wing it is probably make sense to get original Slick.

I have original Slicks, cheap as chips secondhand or heavily discounted new. They don't like being overpowered but as you can pick up a good secondhand one for $400, you can afford to have heaps of sizes and the perfect wing for the day.
The SLS is lighter, but that's not as important in smaller sizes. The biggest wing I normally use in Brissy is a 4mtr.

Rode the 6, 5, and 4m original Slick for a year and a 6, 5, and 4m SLS for the last month. Love the higher tension (l feel like they won't blow out nearly as quickly as the originals) , improved upper end and gust handling, lighter feel (using a 300 gm DIY carbon boom), nice stable luffing and single handed riding feel,...and surprisingly they roll much more readily than the originals during the more challenging upwind transitions like heel side tacks and handle- pass tacks. They don't "flop" as much transitioning to backwinded stuff like 360's. The much more tapered leading edge strut feels way less draggy during those upwind transitions as well. I even like the new bag design more.

If price is a big issue then a used original can be had at a great price, like Airsail said. Sold my original 6m for ~ $450 usd with a standard boom. As also mentioned, if you're short and really sensitive to wing span, the originals are hard to beat.

I haven't tried the original Slick... but I have a Unit V2 in 6.0 and one in 4.5 I recently got a Slick SLS in 5.0 and now have about 6 sessions into it and absolutely love it. The boom is like cheating. The wing feels a lot like the Unit v2, but with a boom. Also, the long windows are better too, and it feels lighter.