I have had a couple of those ‘5.15b’ clone GDEMUs through my hands, and despite being pictured on the auction site with the correct Atmel chip, they actually had the wrong one fitted still, same as 5.5 and 5.15 versions of the clone. Luck of the draw? I’m doubtful. The interface connector was also hacked down to fit, with one of the units being a bit ‘sensitive’ to being positioned correctly. You pays your money, takes your choice. Both worked as expected otherwise. If I had to buy another, I’d go with a 5.15 as long as it had the correct crystals fitted, since I don’t care much for the metal SD connector (and the correct Atmel chip is the selling point for the 5.15b, and that didn’t turn out to be the case).
FWIW I do own a couple of Deunan originals, the others went in systems I modded to sell (with full disclosure as to the provenance of the GDEMU fitted).