High Leval platforms means fast passenger egress and degress. I personaly dont like having to push my bike up and down stairs. The galley double deck cars are unique to Chicago and other cities that use double deck cars do not have open galleys like North Star and MARC trains. I would also reduce conductor fatigue by going with a proof of payment system like LA Metrolink and GO Trains..High Level boarding should be standard at at least the first 15 stations out of the Loop..Seems that a lot of METRA is still stuck in the past here
Uh, the gallery cars used in Chicago are also used by VRE (Washington DC area) and CalTrain (former Southern Pacific commuter line in San Francisco).
Arguably, it's things like people bringing bikes on the train that slowing things down more than the level of the platforms.
Metra might be stuck in the past, but per your own admission, they're one of the highest volume systems nationwide, so they must be doing something right.