I agree with Bill. The length of the layout is not the determining factor. The number of locomotives and other powered rolling stock in operation simultaneously is the determining factor.
The consideration of layout length is due to electrical resistance of the rails and your bus wiring. Heavy gauge wire for your bus eliminates this concern and is considerably less expensive than multiple power supplies. Use 12 gauge wire for your bus and there is no practical limit to layout length.
The repeater functionality is exclusive to RP power supplies. If your layout room contains a lot of significant size grounded metal structures (water heater, furnace, washer, dryer, etc.) or is separated by thick concrete walls then the repeater functionality may be of value. In clear space the HC and LMs have excellent range with no repeater necessary. My train room in the basement is 28x32 with stud and sheetrock walls separating it from the rest of the basement. I can operate from the opposite end of the basement, approx 75' away and through two walls, without repeater.