Oh dangit. My reply got erased.
To answer your question, in a word, no.
First and overdrive are essentially the same for both transmissions, but the gear splits on the 6-speed are closer together which helps get/keep a heavy load moving. Both are really tough, the 5-speed being about 160 pounds physically lighter makes it a really popular swap for extreme off-road rigs.
The 5-speed does have the "5th gear nut" issue, which you can search about.
98 12-valve QCSB 2wd