I'd shop for the best deal I could find on a good, used Excursion 7.3 and never look back.
If the 2000 you're looking at is 4x4 and clean, well maintained, no accident, etc. - it probably won't depreciate a bunch more even with lots of miles if you keep it nice.
An Excursion or other 7.3 that has depreciated down is about as cheap as one can drive, IMHO. They are good for a zillion miles, economical on fuel, plenty of power, lots of room, and reliable and easy to work on.
All 7.3's I've had have been virtually trouble free, and I've had a bunch. I have two now with 350,000 and 260,000 plus miles, and there's not a gasser I'd rather have than either of them.
No question I'd jump to an Excursion. If you're not sure you'll want to keep it forever, a 4x4 will sure hold on for resale purposes.
99 F250 XLT CC, SWB, 7.3, 4x4, 6spd, ISSPro Gauges, old 75 horse TS Performance chip, AFE stage 2, LUK, BTM. 330,000+ and going strong...
2000 E350, 7.3, Auto, XLT, Bone stock (at the moment) 90K
2001 F250 Lariat, 7.3, Auto, Bone stock, 83K, (April 2001 build date - truck and tranny - so no mech. diode, Chip/gauges/intake/exhaust to come)
2002 Excursion Ltd., 100K, DiPricol Gauges, DP Tuner (high idle, 60 tow, 80 economy, 120 race), Ford AIS.
Pretty big 7.3 fan...