I have and changing ujoints on the trail is no fun. If you break a shaft or ring and pinion you can just unlock the hubs and drive home, if you have no balljoints you're not driving anywhere. Ujoints are cheap but the damage they cause when they break can be expensive, besides the balljoints they also damage the ears on the axleshafts when they break so investing in good ujoints is a very good idea.
76 CJ7 6 cyl/t18/Dana 20
05 TJ HP30/8.8 with ARB's Rubicrawler Flatbelly Midarms/3" lift and 35s