I believe that the BoP team is making Spa water unobtainable with regular buckets. I heard watching Direwolf20's server play today that you will need amethyst buckets to get them. This might mean that they are doing other things to limit automated collection of Spa water if they are trying to gate it behind getting to the promised land dimension.
In response to your opening post Shneekey, I do consider Buildcraft to be integral for my MFR farms. I do use the belts a lot in my design, (and could probably replace a lot of my pipes with more belts), but I managed to automate the generation of pink slimes with pipes, thermal expansion and computer craft (a normal turtle as a deployer, the dispenser doesn't work with pink slime buckets unfortunately). However, with the addition of sorting pipes for extrautils, (and being prompted to think about it by this thread) I can replace all the buildcraft pipes with extrautils pipes.
I would like to ask though, does extrautils have emerald pipe functionaility? It doesn't matter if you use a turtle but if there was a deployer or deployer like block in any mod coming out in the future I think the design would need an emerald pipe or something else that has a filter on extraction.
EDIT: Even though its probably obvious, I should say that I don't play Shneekeycraft. I just wanted to offer my thoughts. Its definitely an interesting proposal, removing buildcraft, not sure if I would do it because I have grown to love its pipes but good luck with your decision.