The uk is much like all others country's around the world has its good parts as well as its bad , I'm working on the wife for me to get an action cam off our mobile network I'll bay monthly and it will link to my phone and a supplied watch via wifi plus it has 4G for things like facebook live
The main reason I wanted Diamonds is so I can get proficient in very light winds. I also wanted to try them in my full vent B in low/moderate winds. I'm not quite at the 'yank and spank' level of flying yet, lol.
My only hesitation is that I'm not sure I want to mess with cutting rods to size and gluing ferrules. I haven't done much research, but I would hate to screw that up and have to buy more rods...
I have and fly both. They are two different critters. Your flying style and how you want the kite to respond will determine which is the one to use. Neither one is better than the other, just different. The price reflects the materials used and the wrap pattern, which also account for the differnces in performance.
The one thing that is dramatically different is the response time, how quickly it returns from bent to straight. The Diamond frame is much quicker in response, and therefore more suitable for a yank-and-spank flying style than the P90. Both are lightweight, light wind tubes. In wind of 1/2 mph or less, the P90 will require less "pumping" because of the slower response, and will make the kite move more smoothly. The only way to appreciate the difference is to fly both in the same sail in the same conditions.
If you are just starting out with quads you will probably not notice much, if any, difference. It doesn't become noticeable until you gain a bit of proficiency in flying very light wind. Once you cease to struggle in a 1/2-mph breeze, the difference will become readily apparent.