It seems that both Cherry and Corsair have tried to cut corners in places that are less likely to be immediately noticed by customers. This will still very much yield a lesser quality, and more likely to fail over time product.
-Compared to the original K70, the overall quality of this product is less. The first and most glaring thing I noticed are the stabilizers for larger keys (space, 0, shift, etc) are far looser/poorly fit on the mk2. The black retention pieces (see video) have SO much slop compared to the original. I can only really get any movement on the original if I really force it. This creates not just extra movement on the keys, but it also makes it noisey. Often times, this is part of what gives people that notorious spacebar rattle. As pieces wear over time this will only get worse. Especially for a transcriber, I have several special functions that rely on shift and combinations of shift with other keys. The extra slop is noticeable compared to the first version and I can hear it almost as loud as blue switches through headphones when transcribing audio. Already I have an awful amount of audible rattle on my backspace key, while my original is rock solid.
-A second thing I've noticed is how they've relaxed the tolerances on the key caps and switch stems is. On the original version, it was very difficult to remove the key caps from the switches unless you had a wire puller. On the "updated" mk2, they pop off so easily and can be put back on with so little finger pressure, I almost didn't believe I had them on. This is not a good thing: it will make the caps more susceptible to wear that will create more slop, and overall just does not convey quality. If you've ever had a spacebar that had a problem where overtime if you hit one side of the key and the other side would pop up and stay there, this is why: keycaps/stems with poor tolerances.
-Third, the switches themselves have more play in them than the original k70. It created a noticeable amount more key wobble.
Overall, after a year and hundreds upon hundreds of hard typing and key smashing when raging, my original k70 is still a higher quality product than the new mk2. The tighter tolerances on the original almost make it feel like a newer product than the mk2 I got in the mail literally today. The overall typing experience on the mk2 is just sloppier and it does not inspire confidence in the long run. Some upgrades are admittedly awesome. The clear switches really enhance the lighting, the on-board profile storage is fantastic. HOWEVER, looking at it in terms of the functionality this piece of hardware is required/designed to perform, (TYPING) they clearly decided to throw away some quality in favor of some pretty bells and whistles. If I had never experienced another high end keyboard, specifically the predecessor, I may have given this a higher rating, but in lieu of knowing what's being lost, I can't.
At some level, it's almost insulting that they're trying to pass this off as an "upgrade" when they've reduced the essential functions of their original to something of lesser quality.