I've found that STG cubes dry out waaay faster than say rockwool cubes do. Keep that in mind, especially in higher temps as you'll find yourself with dried out clones rather quickly.
I personally don't like them for that reason as I'd either get them too wet trying to avoid drying out or they'd all just die on me if not watered constantly. Waste of time IMO.
I have used them to pack boxes as fill.