I don't have any use for the super low 1st gear on a 4500. My BIL had a early 90's ford with a 7.3 and I'm assuming a zf5. It was a blast to drive. 1st gear was still a little low though, but it shifted fast and smooth. I've only ever driven the dodge version of the 4500, Is the chevy version different? The other thing I don't like about it is the LONG shift throws. On my brothers dodge, 1st gear would almost hit the dash, and second would almost reach the seat.
The zf5 seemed to have pretty short throws.