Any experience with Krell MDA 500

Looking for your opinion and insights on these amps.
I have used many Krell amps. Some of which I have owned.

The MDA500 was the best of it's time. Much better than the MDA300. They are big and powerful. They can double as space heaters. They should be turned on way ahead of time (hours) to achieve best performance.

That said, they are bettered, by a big margin, by the current FPB's; even the stereo FPB's (especially the bigger two models).