I prefer chainstays that are proportionally correct for XL frames. Barely any brands do this, so usually I have to ride long bikes with chainstays that are designed for Medium / Large bikes.
A XL bike with long front centre and 440mm chain stay is really unbalanced. Bikes should grow both front AND rear for larger sizes - so when bikes have a 455 ish chainstay they actually ride (and climb) much better for me.
Should also note that heavier and taller riders need longer CS, as the additional body weight and ability to get more rearward loads the rear wheel more. This rearward weight bias makes front traction in corners suffer, forcing the rider to be more aggro (e.g. lower grip and with your chin over the stem). Longer CS shifts some of that body weight to the front to rebalance things, so the rider can save more energy staying neutral, ready to execute techniques like pumping. The key operating word here is balance, where things get worse and worse as you get more weight on the front wheel (more OTB risk, front wheel harder to keep level in air on drops/jumps, etc.)
Please don't say say most bikes are designed for Med and Large! I'd agree if you just corrected that to say designed for Large (only). XL has the 2nd largest pool of bikes to choose from, IMO. I find pickings are extremely thin for size med, and forces me to be overbiked to get a WB that is long enough to match the long CS. Tall folk likely gravitate to shorter travel stuff, to get the WB short enough to match the short (to them) CS.
As a lighter and shorter rider, I rarely find any bikes with short enough CS. Marin, Polygon, and maybe Scor and Kona Remote160 are the only options I found in size Med. The Torque:ON has CS short enough in med, but slack STA (74°). Maybe if I weighed 100kg/220lbs (muscle weight, from a life of lifting heavy weights of course ~_^), more in line with a stereotypical American, I might find the long CS on some medium bikes to be decent, able to pick a mainstream option like the Torque:ON or Levo.
Riders seeking bikes in size small... good luck. I found that up-sizing, slapping on a shorter stem, and raising the grip height reduces the weight on the front enough to get a decent ride. Overforking and -2° angleset are also options to reduce the problem of too much weight up front. Else, there's always adapting by getting your butt behind the saddle on anything gnarly; can't really do any techniques from that position besides clench, steer, and modulate brakes though. Without sufficient opportunity to practice technique, you might feel untalented and slow to progress. Maybe consider a Canfield Balance in small with a CYC motor?
IME, I find bikes (29er 150mm) with 1230WB and 435CS to have the ideal balance and WB for what I ride. I'd opt for slightly shorter CS if the rear wheel were 27.5 (maybe 3-4mm shorter CS) or if it were a high pivot. If I wanted some variety, I'd get a bike with a diff WB (1170WB for a playbike, 1270 for a big mountain bike). I know from riding dozens of bikes, including ones with adj CS length, that balance is retained if WB is adjusted by 20mm for every 5mm of CS change. In short: 440CS still feels balanced to me if the WB were 1250, 430CS with 1210WB, 445 with 1270, 425CS for a 1190WB, 420CS 1170WB, and so on.
That Simplon looks great, except it's too rich for my blood. I love the quiet motor and clean elegant look, but try again in alum at under $6000! I'm waiting for an utilitarian build, with Linkglide 10spd, a good fork chassis like a base Zeb/Lyrik (or Domain/Yari if they receive the same updates as '23 Zeb/Lyrik), and MT520 brakes. Everything else can be budget/no-name placeholders. I'd take a mullet rear, as long as it's not a plus tire nor some compromised design convertible to 29 rear! I'm sold on short cranks, after adapting to 152 cranks, so hoping to see something similar. The Alpine Trail E2 was on top of my list for a while, but now I'm waiting for a TQ HPR50 or eventual HPR80 instead, with a battery setup that can go 4+ hours with eco mode on the flats, and adaptive/trail mode on the climbs.