I've not changed the bearings, did think about it when I had a swingarm problem but they looked and felt fine so I left them.
As to the pivot/spindle, the clips on the end stop it sliding out if for some reason it comes loose.
Check out my cracked swingarm thread for more info:
http://www.ukmonster.co.uk/monster/s...ad.php?t=60544
Whilst it didn't, mine could have come out far enough to cause me to crash. Obviously the cause of it coming out was the swingarm cracking but had the spindle had the circlips on each end it would not have slid out.
To add, as the pictures show I did have the circlip type spindle just that my swingarm didn't allow for them to be fitted, the new one does and I'm happier with that setup.