I got a package quite similar to yours a couple of days ago (it must be my 7th or 8th purchase from Chai so far).
My rails are also not drilled (this is the first time they come like this). I actually like it, and the reason for me not asking for it before was the fear of a misunderstanding resulting in me getting "blank" rails too (I don't have the proper equipment to drill and tap such rails). The rails supports and blocks are a little damaged (only the aluminum parts), but not much. I noticed that this time my 16mm blocks came with two set screws (top and side), while a set I got a couple of years ago only had one on top.
Ballscrew machining is amazingly smooth as always, and apparently according to specs.
I bought 14 blocks this time instead of 12 (I want to use 3 on each gantry side to help reduce racking), but I got 12, I think it is an understandable mistake considering that's what must people buy. I notified Chai, he apologized and the next night I had the tracking number for the missing blocks at my inbox, nice!
It's pretty common for the screw's machining to be a tight fit on the blocks, I use some wet sandpaper and they work great afterwards (maybe they can just be pressed in with the proper equipment, without sanding). I'm perfectly fine with oversized diameters, since undersized diameters would be a PITA to fix.
Some BK blocks can have internal play sometimes, it can be easily fixed by adding a couple of shims to create preload. I usually disassemble the blocks to check that the bearings at actually back to back, add some grease and shims if necessary.
IMHO, it's really great stuff considering the cost. Not perfect, but I'm willing to spend a few hours or days tuning things up if that means not having to pay way more than twice for the "real" thing. I'd love to see picture's of the facilities where they do the machining of the ballscrews.
BTW, if you need wider hole separation you can ask Chai for TBR rails (similar to SBR, but the support's base is wider).
This is what I got: