Tom Hamilton changes quite a bit in concerts, I think he just likes variety and is not a 'one bass, one brand"-guy at all. When I saw Chris Squire on the Fly From Here Tour, he changed between his trusted Ric, his newer signature model and that 5-er with the weirdly organic shape. And you heard the differences too.
Geddy Lee changes a lot nowadays too. There is nothing wrong with that if it affects your sound or if you need a different scale for a particular song. Jack Bruce changed between his Warwick Thumb long scale fretless and the EB shortie during the Cream reunion gigs. That other Warwick in a long scale EB look never got played around that time (it might at the Madison Square Garden gigs) because he wasn't yet satisfied with the sound - her left it in the stand on stage.
Roger Glover changes sometimes his Vigiers and occasionally digs out his old Ric for an encore or Smoke on the Water.