I can't comment on any of the 'diecast' KOs. I did buy recently a Shockwave KO, which looks absolutely GORGEOUS by the way on display. I'm on a disability pension, so there's no way I could -ever- afford to buy a MISB version, and can't touch/play with used ones.
But competent? Quality? It's a pale imitation. The electronics in him makes an ANYONING as hell sound, and the "sound selection" switch is missing - I suspect they never were able to reverse engineer the originals, and figured once its sold only a few people would even take him out of the box. His feet are so loose that when in gun form, they drop out again and just hang. The lights a re a little dodgy and flash too quickly. Joints are too tight or too lose. No sticker sheet, no metal Decepticon logo. And from a distance, the box looks actually really perfect. Turn the box around, and you'll find the "top" of the box is about half an inch too tall for the printed back matter, so you've got ugly blank cardboard.
I never bought any of the other reissues, so I can't say whether some of them are "better" in quality. But the joints on encore issues are perfect, and they've even IMPROVED defects in the original toys eg. Bumblebee's face in the minibots.