They are different than the mechanical version.

Good to know! How is the downshifter lever on hydros? May be those are better built that cable pull version.

Staying with anecdotal observations. I never had issues with pressfit and if so I would have either bought a bb with a threaded inner shell - or simply glued in the shells with Loctite 683*.
* "wtf?! You would end up having worn bearings and therefore a frame to be dumped." Actually no. I just use a good quality bb with replaceable bearings.

Hmm. My experience is from BB30 but I am not alone. I have CAAD 10 and SSE2 both from 2014-15 timeframe. The CAAD came with squeaking bb when I bought it last year. Punched out the bearings and installed new (Wheels Manufacturing ABEC-5) and after a couple of months they started squeaking. I haven't changed it to thread together yet so I clean and lubricate every time squeaking returns. The SSE has Token thread together BB on it and it works fine. Its still technically press fit but I like the idea of two cups attaching to themselves than just latching onto frame.

The problem with BB30 and BB30a bb shells is there is no traditional bottom bracket as such - its just bearings pressed in and a c-ring prevents them from going all the way in. Those bearings, c-rings, and two cups/reducers to space out crankarms form a bottom bracket. If Loctite is used it will be around the bearings directly and if it bonds the bearings to frame, its frame dump the next time bearings need changing. Loctite is a big no there. Same thing with Trek's BB90.

When you say I use good quality BB with replaceable bearings, are you talking about BB386/PF30?

Those look like 40mm Ramblers in the photos, and it's already really close to the FD .. will a 45mm really fit on the rear in 2x on reasonably wide rims? I have my doubts,

Are you saying all that from this photo in question?

The BSA bb is rather a downside to me as bonded inlays have the potential to come loose. And then you are in more trouble than with a poorly fitted pressfit bb.

Have heard BB shell bore not perfectly round but haven't heard threaded insert coming loose. For me manufacturers going back to threaded BBs (BSA, T47) is a very welcome news.

My SLT wheels are very loud too. Opened the hub and greased everything but unlike some other wheels that didn't dampen the sound at all. It's comparable to Reynolds hubs on Reynolds R3 wheelset. People will hear you definitely and while working indoors it will scare the cats.

How do the Zrace rings save 20g? Is there a different model I can't find?

Fwiw I can't find any real lightweight rings on Aliexpress Zrace or others. Even the Cybrei comes up *only* if I specifically mention word Cybrei in search box other wise its just generic chain rings.

At this sale price point, I'd consider getting a spare ER9 groupset. I really need to stop looking at AliExpress! lol

I ordered for the second time this afternoon after first purchase debacle. The groupset literally shipped in 1 hour after placing the order. I *really* hope they have removed the batteries this time.

Unlike Anniversary sale, the EGR this time is ~$1 cheaper than ER9. Both down to $370 - $50 coupon. The deal is back. On the other hand all EDS TX groups from 2-3 different vendors that I had added to cart before sale have expired just today. So no dice on them at least in the USA.

Can the supplied BB be discarded and a fresh Shimano branded one be used (as long as it’s to BB386 spec?) if so are threaded/press fit BBs interchangeable? Sorry for the stupid questions I’m new to building bikes.

Thanks!

Supplied BB can be discarded and other one can be installed - yes. Also press fit and threaded BBs are not interchangeable that is why people pay special attention to what sort of bottom bracket shell is on the frame they are considering. The press fit bb shell will not have threads to install traditional threaded bottom bracket like the good old BSA 68MM or T47. The BB386/30/92/86 etc shells don't have threads at all and they all rely on "pressing" the cups into frame rather than threading hence the name.

Having said that, to add to confusion there are certain "thread together" bottom brackets that you can install in the press fit type shell. The important distinction here is the bottom bracket cups don't thread into frame (like BSA) but rather into each other as in both cups tighten into a metal tube that attaches both cups. Look up Token Ninja BB386 thread together bottom bracket or Wheels Manufacturing thread together bottom bracket. These type of bottom brackets take care of creaking issues that lot of people face on press fit type shell.

Also it's easy to adapt already installed bottom bracket to different types of cranksets. You just need correct sized bearing adapters for your bottom bracket. That's exactly what Elves is doing when they give you option of different bottom brackets. E.g.You can install Shimano crankset in a BB30 frame with help of 30mm to 24mm reducer cups
Same applies to BB386. You can get 30mm to 29mm reducers to install SRAM cranksets.

Check what sized crankset you are eyeing and get the reducer adapters on your own or ask Elves to do it.