I'm falling in late here and honestly, I haven't read the previous 8 pages in this thread, so I hope this isn't already mentioned.
My first impression is "Wow, this installer looks good!" I'm from the old original console installer days.
The Gparted section was confusing though. Once I had partitioned, there wasn't an obvious "Next" step. I had to know that Gparted was a separate app and Exit it from the odd menu embedded within the middle of the window. This isn't obvious to new users IMHO.
Is there any way to know that the partitioning is complete so that the Next button can be used to close gparted and go to the next step?
I'm installing now and hoping that setting partitions as bootable is still later in the process, because I didn't see it in gparted.