Possible upgrade path?

Hi, does anyone have any comments on this possible upgrade path:

What I have now: Rotel 6-channel amp passively bi-amping Keilidhs.

I was thinking I could, in order:

1. Swap the Rotel for a 5125 and passively bi-amp the Keilidhs with that.
2. Get some aktiv cards and actively bi-amp the Keilidhs.
3. Get a second 5125 and tri-aktiv the Keilidhs.
4. Swap the Keilidhs for Keltiks, with "double-bass" as I would already have enough amp channels.

Can anyone comment on this? Good? Bad? Are 5125s up to driving Keltiks? What might each step cost me?