Fleet radio, far from not taking off, was the gear of choice for many modelers. The range spaned many years, I would guess around 20 plus. Very good build quality and reliability for the time, I still have a 40 Meg set, over 20 years old that has never had a fault and is as good today as when it was built.
I have Fleet, and Futuba crystals, both are fine. As far as I know, any single conversion crystals are OK.
I hope that helps,
Chas