That bigger pan with trap doors, crank scrapers, oil cooler, HV pump,...that's a different story. One thing alone can be dismissed but several things combined...Especially since you can reuse those parts once its been rebuilt.Bigger pan isn't going to do much, if anything, for "low" oil pressure. Obviously more, cooler oil is going to increase pressure, but I wouldn't expect an extra quart of oil to make any noticeable difference.
Course you could add some Lucas oil stabilizer...I have a 2002 Chevy Astro with 355000+ miles because of Lucas Oil stabilizer added when the oil pressure started dropping. That was 75000 miles ago. 355k is to the moon and half way back. Now granted those havent been hard core wheeling miles but that is with a 4.3L V6 and spent quite of abit of time gross overloaded up and over the coastal mtns.