I had a chance to use the 17mm Stratus this past Saturday night. The scopes we used this ep in was my SV115 f/7, and a friend's Teleport 14.5" f/4.5.
Now, keep in mind that we are both former owners of a lot of Naglers, and we both own pretty much the entire line of Pentax XWs. To say that we were both impressed with the Stratus is an understatement! The first thing that I noticed, when compared to my 20mm XW, was that the Stratus, while displaying contrast that was almost as good as that in the Pentax, showed none of the field curvature that the XW did. It's funny, but I never had really paid much attention to the field curvature in the XW up until then.
On Jupiter, the Stratus showed a nice neutral tone, much as the Pentaxes do. I really liked this aspect of the Stratus, as I don't care for "warm" eyepieces when viewing planets.
At any rate, I was impressed enough to order the 5mm-21mm Stratuses the next day. I will compare them to the Pentaxes and then decide which ones to keep. I think that their may be some surprises in store. IMO, I think that it's great that eyepieces of this quality can be had for such good prices.
On edit: I forgot to mention that the 17mm was one of the most comfortable eyepieces that I have ever used. The eye relief seemed a tad shorter than the advertised 20mm, but I found it to be just right.
I own the 8mm, friends own 5 through 21 and all are very happy; my scope is a 12" f/5, one has an orion 12", another a Hardin 8" f/4. So all were used in relatively fast scopes. Sky conditions have not allowed a real test so the jury is still out, but everyone claims pretty much good focus nearly to the edge. I also have the Baader Hyperion 13. You can check my post #420839
I bought the 21mm Stratus a couple of months ago, for use with my Meade LX200 8' F6.3 SCT. The views through it have been really fantastic, and my poor set of Meade Plossls don't get much light anymore as a result. Images seem sharp to the edge, although I do notice a little bit of flaring on occasion. The Orion Nebula is astounding in this eyepiece, as is M38. I just purchased the 13mm Stratus but due to exams and cloudy nights it hasn't seen much use. However I must say I looked at the moon with it last week (74% gibbous) and it was delightful. Filled the eyepiece FOV and presented a very clear, sharp image. I will most likely get the entire set over time.