I need to make an update post here about the board, because it’s finished! But I’m short on time right now so I’ll just give a short review of the Apex jump drives!
First, the sound profile. Unfortunately they are loud, because they are steel on steel. However they are nowhere near as loud as steel straightcuts, where you can’t even have a conversation with the person using them. And they also don’t suffer from the god-awful free-roll sound most steel gear drives suffer from, that sounds like scraping / rocks inside the drive / more like chains. These drives sound really good, and at low speeds you can even hit a “silent” sweet-spot. I think most people will be very pleased with the sound profile of these drives, even though for me it’s the biggest downside, because I prefer a completely quiet drivetrain. (And spoilers: there are no other downsides! 
)
Also, because the drives aren’t silent, definitely get Apex motors for these. The flipsky motor resonance sound really doesn’t matter if the drivetrain is nearly as loud.
Also also, I’ll record a video later showing how these drives sound from a 3rd person perspective (no wind noise).
Freeroll: It’s… amazing! Granted, I am running 9" tires, but the drives spin so well I could nearly get my robogotchi to completely boot up with the whole startup jingle just spinning the wheels by hand 
(I’m running 5.5 ratio btw) While riding I can safely let go of the throttle and barely even feel the board pulling me back. Very confidence inspiring when in bindings!
Assembly: Takes some time at first, but is nowhere near as cumbersome as Moon drives with all the spacers, and the instruction manual is very helpful. Also the apex motors with the 2nd circlip groove for holding the motor pinions in place – absolutely genius! Not having to get a torch out to do a motor / pinion swap is soooooooo nice!
(I did have one motor with a slightly longer shaft, so I had to steal a small shim from another motor to get a tight fit. Would be cool if Apex included some shims in case others have the same issue)
Design: The drives look sexy and they don’t weigh much either. Ground clearance is great. 10/10
Attaching wheels: I’m a firm believer that all drivetrains going forward should allow wheels to be quick-swapped. This is why my travel build is getting these drives, because tire changes on the side of the road are a total breeze thanks to this feature.
In conclusion:
This is THE BEST ESK8 DRIVETRAIN ON THE MARKET, hands down. For most people this is a no-compromises drivetrain only made better by Apex’s fast shipping times and excellent customer support. Unless it’s a urethane board, this is the only drivetrain I am buying going forward. It’s that damn good.