I've had the chance to test a lot of parawings while Vayu figured out the Pyro and personally I would say the Pyro and the Duotone Stash V2 are going down a similar rode. The Flow D Wind V2 and Ozone Power Pack are going down a different road.
The Pyro punches above its weight in terms of size. You can get away with a smaller parawing in the same conditions when compared to the D Wing V2. The Pyro has more power down low and you can angle much further upwind for the same sized alternative. The disadvantage is you are likely to become over powered earlier, basically you need to use a smaller version before others. To me this is a huge benefit as why wouldn't you want to use a smaller parawing?
The advantage of the Flow D Wind V2 and Ozone Power Pack is if you are only going out in really windy conditions it is much harder to be over powered as they handle being powered up a little better than the Pyro/Stash V2. The disadvantage of the Flow D Wind V2 and Ozone Power Pack is if the wind drops or it is not such a windy session then you are going to struggle to get going and struggle to get upwind.
As I mentioned all parawings are getting better and personally I am a big fan of the Vayu Pyro for my conditions. I used the Flow D Wing V2 a fair bit before the Pyro was released and I could get used to that as well but it was different and I was riding a bigger parawing to get the same amount of power but it handled being over powered really well. You need to decide what kind of conditions you go out in and if you are more likely to be riding over powered or under powered. You then need to really wrap your head around what sizes you need to use for what conditions as there are two different types of parawings emerging and you cannot just use the same size as your mate who is using a different type of parawing.
I did a review of the Pyro if you're interested
