I've been using an Orchard Audio Ultra Amplifier for going on 2 years now with no issues sonically or reliability wise. GaN FET is where things are going as traditional high power MosFet type device are becoming depleted with many companies no longer manufacturing certain part #'s anymore.
When implemented correctly, they can sound as good as Class A, Class AB, SOME,,,NOT ALL Tube designs. The market is getting crowded as more high profile manufacturers are either looking or already developing/selling GaN FET Amplification.
As the other GaN FET forums here have outlined. Out of the box, they sound amazing. With some next level Audiophile tweaks (signal path Capacitors, signal path wiring, and even binding posts/XLR/RCA connections of a higher grade than the stock offerings.
They can become something special at a huge weight savings. Switching or Traditional Power Supplies. One works just as good as the other. Pick you weight class !