Actually I'm looking for a standard that can handle lower winds better.
The SF seems to require more than 5MPH to keep afloat, so maybe I'll keep the SF for higher winds.
You can take out the top spreader and tail weight to drop the wind range, but it still will not be an UL.
Also, partly because I do not want to go for actual UL yet. I thought maybe Krystal can reach a lower wind without switching to weaker framed ULs...
Better to think of UL as a lighter frame, not weaker.

Not much stress on the frame at 2-5 mph vs. Silver fox at 15mph

UL's are not built for abuse but can last for years. Never broken a rod in any of my ULs and the oldest is over 10 years old. Based on my local winds, I'm flying a UL 60% of the time. Thats a lot of quality air time vs sitting at home waiting for wind.