Originally Posted by poiuyt

Changing the cassette to an 11/42 will require your to adjust the b-screw of the derailleur, or install an accessory like a goat link if your derailleur can't handle it. This is where the shifting performance will decrease (but generally speaking, a Deore will still shift better than an Altus or Acera — no need to go for the M5120, the M4120 will do as well, you don't need the clutch on a 2x). The difference between 11/42 and 11/36 is significant uphill, yes, but more in the sense that it makes long uphills less strenuous, on technical trails, the limit remains the rest of the bike. I changed the entire chain, because I went from 2x9 to 2x10 — it was worn anyway. Although I tried at some point a microshift advent 11/42 9 speed cassette, and the shifting performance was too problematic, but I wanted to keep the 11/42. So the choice was either to stay in 9-speed and go for an Advent or replacing the cassette and the chain as well and go for the Deore. I chose the latter because of the availability of parts: Microshift is not widely distributed here.

Now if I were to do it in "today's market": yes and no. Note that the 2020 DS has a bottom bracket shell of 73mm (from 2021, they have 68mm BB shells), so this crank is currently the only 46/30 available. The increase of range and upgrading to better components was worth it. Note that what I did was the only choice if I wanted to keep the 46/30 cranks (and I'm off-specs in terms of rear derailleur capacity). On newer DSses, there's another option, but that requires changing the whole drivetrain in one operation: a mullet with GRX cranks and an XT RD-M8000-SGS rear (that can handle 46/30 front and 11/42 rear within specs, and possibly even 11/46). But the new Shimano CUES seems more interesting: 46/30 cranks and 11/45 cassettes, but components are not available yet, so I'd wait for that in today's market.