My experience is similar to that mentioned in Post #7 by Thomas.
I will only summarize my experience with this format (6x7cm neg) and 20x24 prints:
You will need a 90mm enlarging lens - a 75mm will not cover 6x7 - a 100mm or 105mm would be even better. These lenses may or may not allow you to project a 20x24 image onto the baseboard, especially if cropping is required; as already mentioned, there are ways around those limitations.
20x24 trays take up a lot of room! Toning and washing has to be done pretty much one print at a time unless you have a 20x24 archival print washer (a monstrosity). You need a lot of chemistry - I use 3 Liters of solution per tray, some trays with deep bottom ridges require more.
Handling prints - moving them from one tray to another, takes slightly more effort to avoid paper damage; I have creased a few.
A 6x7 negative has enough information to print onto 20x24 without degrading the image, especially if you are using films like T-max, Delta or Fuji ACROS. I have printed a few 6x7 and 6x9 negatives to this size with very good results.
Sometimes you need to print large to see what size limitation you image has - not every subject matter looks good printed large.