Hey Raf.
I am using a Futaba Gy352 on the outer surfaces of my Mirage 2000 ( I have 4 surfaces mixed as elevon) and it has transformed the model. I have to admit though I have yet to fly a delta or taileron model that needed them on pitch. It has always been roll control where they felt a bit fidgety and unstable. A good quality gyro really helps take care of this, and make the model so much more enjoyable to fly.
A saying I quite like is " A gyro equipped model will hit the ground through cack flying just as easily as one without.. It's just that the one with a gyro will do it smoother and in a more locked in manner"
Let me know if you need a 352. I don't know if you have anyone heading out to FJ next week, but I could pass it to them to bring to you if you want?
Regards Al