HIStoryAkai Japan incorporated SHIFT and Window buttons in MPCs since the late 1990s. The Mode button was added in the mid 2000s when the MPC 1000 was released. Its impossible to have a dedicated button for every function. These buttons are used to access secondary functions of pads and buttons. ALL physical samplers/workstations have either a similar SHIFT button function or dedicated buttons with layers of hidden menus. For the Ren, Akai sought to add one-button access to the most frequently used functions. I think Akai are pretty much on point but I would have preferred a dedicated Sample Record button and dedicated buttons for Pad Banks E-H. The 4 buttons dedicated to Data select for file browser is overkill in my book.
The location of the SHIFT button was never an issue IMO. The change of position does absolutely nothing in feel and workflow. In fact, I would have moved it down closer to the transport buttons like the MPC 4000 and 2500. That way I could have my thumb on Shift and use my other fingers to access secondary functions of other buttons.
'Half full level' button? Full Level is found in every MPC ever made. It allows samples to be triggered at a fixed velocity of 127. Shift + Full Level activates Half Level to allow samples to be triggered at a fixed velocity of 63. You actually took the time to address this 'feature'?
Overall, the MPC Ren is pretty basic to anyone that has experience using an MPC. There are some aspects of the sampler (program editing) that isn't as powerful as the MPC 4000/5000. But there are great improvements to Sample Editing, Mixing, Automation, Effects, etc that exceeds every other MPC. The new and improved punch-in feature is something Akai should have done a long time ago. And additional new features are coming.
By the way....if you have some ideas you would like to see, add them to the feature request thread. Akai is actually listening and every feature suggested in this forum has been sent to project managers/developers.

Its a great day to me an MPC user....