FSGRW does what it says on the tin. It is very pleasant and simple to use, no flashy interface and a plethora of options to adjust like Active Sky or REX. And the weather representation has always been very good in my experience. It is the engine I'm using currently for V5.
The main catch with any weather engine at the moment is seemingly a bug in V5 with extreme upper wind shifts. Only work around right now is to simply disable upper weather layers in FSGRW or other weather engines.
So, it's a fine product. Price might be a bit on the high side nowadays though if you are purchasing new and not upgrading. So yeah, wait and see what HiFi will bring or what REX will do. But it is definitely not a waste of money or a "late upstart". They've been around for years and know what they are doing. My first purchase of FSGRW was in 2013!!