Without having to adjust chain length? I.e., set the chain length for 11-34 and leave it when using 11-30. Too much slack (2/3 links maybe)? I’m running 12 speed Ultegra Di2 so derailleur adjustment should be a breeze.
TIA.
Should be just fine if set for the bigger cassette, mainly because you’re hopefully never running small x small. That’s where you’d notice it if it was problematic. I’ve lazily done it for both road set ups and mtb chainring swaps and no problems. I think my neo has a 30t on it instead of the 34 on the speedmax right now.
*edited to add: plus your 34t cassette still has an 11t anyway so your derailleur can swing it either way
Agreed. Have done this. Works fine. Super slack on small small but nobody ever shifts into that gearing unless their di2 is about to die anyway. 