I agree that non-EFIS for MCC is better. There is not time on a 20 hour MCC for the pilot to become totally familiar with the operating environment and the transition is eased with a conventional aeroplane.
I used to teach MCC on an EFIS equipped jet sim - now I teach it on a conventionally instrumented turboprop sim. I am pretty certain that EFIS is a disadvantage but I am less convinced (now) that jet is an ADvantage.
We used to have a lot of trouble with the pace and performance of the jet sim - it could be hard for trainees to keep up with it to begin with and this got in the way of the MCC teaching - SOP, situational awareness etc. The (slightly) slower pace of a turboprop is a good step up without being too big a leap. The step up to a jet is then not as great as many people would have you believe.
If you are doing a full blown Jet Orientation Course then the situation is different - 50% or more of that course is likely to be manual flying, learning jet performance and jet handling and if you know that you are going onto a jet later (as our sponsored cadets were) then it was valuable.
As an illustration, my multi-engined pilot training in the RAF was carried out on a Jetstream Turboprop. After graduation with my wings, I went straight onto a 4 engined Jet and found the transition to a jet to be no trouble at all - despite being only an "average" pilot. However, what DID cause me difficulty was getting used to working as part of a 4 man flightdeck crew - our MCC/CRM was "picked up" as we went along. An MCC course on any sim type would have been a huge advantage at that time.