That's a really handsome bike; I love the paint.

I'm so curious to see people post and review this frame here, but it just doesn't seem to materialize. 

I'm less worried about breaking the frame and more worried about a loose rear suspension that creaks, clicks, pops, and wiggles after some amount of time. Heck, I'm worried about that on the real Spark, the Chinese clone, even more so.

For what it's worth, I now have 842 miles on my 2023 Spark Team. Frame and suspension have been flawless with zero trouble/maintenance needed.  Headset cable routing has also been fine.  Only consistent issue I'm having is with the Chinese clone Syncros 1-piece stem/handlebar setup; it clicks unless you grease between the stem/steerer tube regularly.

The lights i've got from aliexpress have been pretty crap for their price, the bikemate lights from aldi which are $20(?) aud for back and front light have been very solid.

Check out the Gaciron I posted above. Not cheap, but very much a premium light. By far the highest quality I've found on AliExpress.

I've been very satisfied with my Gaciron headlights.  I've had two I've been using since 2021 without issue.  I think they're just starting to convert their lineup to USB-C.

I have a V9D-1800 and a V9M-1200. 

This is their official store, but other vendors have their products for a bit cheaper.

GaCIROn Official Store
https://a.aliexpress.com/_mP52W5K

I think the big thing is what does cables through the headset gain you?   The answer is nothing of value  and only more headache.  There are a fair amount of negatives and the only positive is it is "cleaner". Except all those cables still loop out to your levers and shifters and remotes anyway.  Now the just coalesce at the stem instead of 4" lower in the frame.

Perhaps.  I just really don't see it as that much extra headache for me.  It was a marginally longer process to take things apart. And I do that basically never (possibly because my use case is hot/dry Arizona where maintenance just isn't needed on items in that area). 

What negatives have you identified with your headset routing?

I value the marginally cleaner cockpit I suppose.  And as cockpit controls start to be designed with this in mind (see the new SRAM brakes where the brake line exits the lever basically on the bar) tucking cables out of the was will be even easier.  Couple that with AXS shifting and droppers and soon wireless lockouts, and a single brake cable is all there will be to think about.

For what it's worth, when I disassembled everything, I removed the brake lines from the levers and shortened them.  I didn't even need to do a full rebleed of the brakes. Simply do the simple shimano lever/cup  dirty bleed and everything was perfect. 

I guess I'm curious as to what everyone is doing with their bikes that they need to be changing out that upper bearing so frequently. Because that upper bearing is really the only thing that is even marginally more difficult to change out than routing cables through the sides of the frame.

New group set is sick, Cabonazza. I irrationally want to upgrade my 3 month old X01 AXS setup.

I definitely will upgrade to the new trigger pod even if I keep the 'old' derailleur.

I've been watching the cranks for a few months now hoping for some reviews to roll in. I'm interested to see if they are junk or not. 

Is it aesthetic or do you feel a difference when pedalling ?
Or both? 

I noticed no difference really.  Maybe a bit smoother. But likely placebo. I think it's a looks thing.  And weight.

On the (now old) AXS derailleurs, The only difference between XX1, XO1, and GX are color/finish and lower cage material.  The actual mechanism is identical.  So the lower cage material is what explains the weight difference between each level. And there's an approximate 70 g difference between XX1 and GX.  Any of these aftermarket oversized pulley cages will lighten the GX to be the same weight as the XX1. And for considerably less than the XX1.