I have and it makes a huge difference, especially if you do your homework and install PUPs and a pre with voicing to your liking.Considering gutting my bass and upgrading pick ups and preamp. I have an Ibby with the Bartolini BH-2 pups and Ibby active pre-amp. Sounds pretty good, modern ... but restricted.
Not asking what do I replace them with but rather did you notice a big enough change in tone and presence to warrant the expenditure?
Let me know...
On a side note. It sounds like you have a BTB with the BH-2 and Ibby pre. I have and have had a couple of the Premium IBbys with the Nordstrand Big Singles and ibby Pre. IMO the Ibby pre makes them sound modern, but very electrinic, not very warm or organic at all. I’d say if you want a change start with the Pre and go from there.