Haha, I love Youtubers. Great stuff and super informative.

FWIW, I ended up going with a Quarq Dfour DUB. Had to fork over some funds for a DUB crankset, and ended up keeping my Shimano chainrings, but In The Know Cycling has a code that saved 10%, free shipping from a local vendor, and a delivery time that had the set-up installed and working on my bike 3 days after I ordered it. No installation, fitment, or functioning issues. Would have loved to go with a more budget friendly option, but considering everything, I think it was a wash.

Can you update on this, I'm curious!

Yeah, it works, no problems! I fit the bearings and the lock ring, used the FSA compression plug, and tightened it all.down with the TanTan headset cover and handlebar spacers with no issues. I had to use some micro spacers with the lock ring, but that's not an FSA fitment issue.

The image I posted was for the Falcon Pro AR55 rims and wheelsets.

 It is listed as being 28 mm wide, but since it's U shaped, it's actually 30 mm at its widest point. If you are following the 105 rule, it makes a difference running the 25mm Conti 5000 TLs. The 25mm 5000 TLs pump up to around 28mm wide and sit flush with my AR 46s. Looks nice and tidy, but apparently not aerodynamically optimized.

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Yeah, I have nothing but good things to say about Light Bicycle's service. I ordered mine through the North American Wherehouse. I just wish they had a wider selection of their road Falcon Pros. If they offered 30mm wide deep section road rims, I'd order a set.

Echoing what Carbonazza said. I'm 178 cm with a 81 cm inseam. My choice was between a 56 and a 54. I went with a 56. Either would have been fine for me personally, but I don't have a lot of flexibilty. I can run a reasonably racier stance on a 56 with just a 100mm stem and just one 10mm headset spacer. I'd could have run a longer stem but I'd need a few more spacers.

Hmm. I did another search but couldn't find it in the $200 range. I think I mistook another model for what Rolling Stone calls their FSA ACR compatible "Hider" handlebars. The Hider is listed for $350 ish.

Well, I have the FSA ACR headset so I can't say if that's what comes with the A9. If the A9 set-up is not the same, the genuine FSA ACR headset is a worthwhile $50 investment. The FSA compression plug doesn't slip and is definitely longer than the TanTan plug, which is most likely the same as the Velobuild set-up. The FSA plug supports the stem better than the stock plug. I feel like all the FSA materials are just higher quality than the stock TanTan components for sure.

Way more important than the individual components, though, is the way the FSA headset/Metron handlebar system works together. Instead of trying to cram all the the tubing and cable housing through one narrow choke point through the compression ring, the ACR system routes the front hydraulic brake tubing through the top of the stem, over the top of the steerer tube, through the compression plug, then down through the tube/fork. I have to believe the FSA/Metron system is easier to work with and won't cause the same problems with tubing/cable routing.

I'm just not willing, at this point, to fork over $400-$500 dollar's for a set of Metron handlebars to fit on my $550 frame and budgetish build. Along those same budget lines, I suppose if you're gonna go with electronic shifting, it won't matter as much as far as I'm concerned.

I found a fitting that allows the housing to leave the frame.

Where did you get it? The stock fitting is a pain.

The 105 shifts flawlessly when it's adjusted correctly, really nice, but mine had a tendency to need readjusting every few rides. Might have had something to do with the fiddly cable fitting. I switched to Ultegra and have had fewer issues with adjustment, but I also spent a lot of time securing down the fitting when I switched out the mechs.