Hmm, never heard of the Requinto. But I do own a Mele Guitarlele. Its riding in an old Kamaka-style baritone case. I can tell you that it blows away the Yamaha Guitarlele. I have mine tuned to EADGBE, but the strings are a bit pretty loose, and I might be able to crank it up 5 half-steps, but I have never tried it, and know that I'm too cheap and lazy to replace strings.
But my overall assessment of my Mele, which retails for something like 700 is that the guitarlele really is not that good of a compromise between guitar and uke. Granted, I prefer the sound of steel strings over nylon classical strings. But really, after playing a full size guitar, ones that retail for half of what the mele goes for, the Mele just cannot compete. Yes, this is an apples to oranges comparison, but still...the overall instrument just isn't a very enjoyable experience IMO.
The cool part is that you can play it with your right hand pretty much just like a uke, with you regular strum pattern and chunking and everything. And it's a cool way to learn guitar chords if you're making the transition. But really, the sound just doesn't do it for me. I just brought mine out and gave it a few strums, and I'd say the sound isn't as full as a guitar, and not as bright and precise as a uke. Yeah, I can't really describe it, but Ahnko, if you happen to have a good electric bass or a solid-wood Taylor/Martin acoustic cuitar lying around in your closet, I might be willing to trade.