I prefer the bigger speakers myself, don't want anything under 8" diameter although some of the 6" ones sound decent. Really like the 10 and 12 inch for guitar and 10 or 15 inch for bass.
Sometimes I put my Ruby through a Realistic 20watt PA amp a buddy gave me and play it with a old Fisher 20watt 10" speaker I found at a Goodwill store.
I do think these Ruby amps sound better than the Lil Gem and Smokey types. When I get a chance, I'll try that JFET on the output side.