The biggest issue with the München-Nürnberg Express (quite often referred to as MüNüX) at the moment (or pre Covid...) is a lack of capacity. Running an hourly service would be quite expensive (access charges for the high speed line from Ingolstadt to Nürnberg are more than three times higher than the average Bavarian regional lines!) and running longer trains is not possible becaus of short platforms (especially at Ingolstadt Nord, slightly less so at Kinding and Allersberg), which is why they are supposed to get double deckers in the first place (they needed 550 seats on 165m long platforms!). Loco hauled trains are quite good for this situation, as the loco does not have to stop at the platform and one does not loose space inside the train for traction equipment.
For the quite comparable RE from Nürnberg towards Coburg via the high speed line, DB Regio has ordered 190km/h Desiro HCs, which could - in theory - also be adapted for usage on the MüNüX - but money might be an issue with that plan...
If you are lucky and get one of the very few (between one and two per train) standard class compartments, the current stock is very nice, especailly as it has a quite cheap (for on board standards) catering service.