The old William Optics ZS66SD - White trim model with black focuser was equipped with FPL51 glass but the mating element must have been a good one as there was no bloat or any blue cast around the stars.
Similar results I found with the SW ED72, wonderful optics no blue casting around the stars but the build quality could be better.
Other options are on the market, but I am still weighing up should I need to buy another scope?
That's why I stuck with my Celestron ED Refractors and probably still will.
You could really have a good refractor optic with glass other then fpl53 so long as the mating element(s) are of good optical quality and correction as well.
Take for example the WO Megrez 72, the original design of the scope belonged to long pern (probably still does). It was equipped with FPL51 with another glass element but showed some blue bloat around stars in images (I know because I had one).
Another telescope manufacturer now manufactures them with a modified lens cell which does not pinch the optics with FPL53 and NBM51 glass, looking at the test images there's now no blue bloat and more likely better now for the optics to handle using a scope with a quality reducer bringing the scope down to f4.7 from f6.
It's all swings and roundabouts. Marketing Hype is included for free !
Just my 2pennies worth.