I used build craft for everything in my last world, until a pipe overflowed we everyone was offline.
So... now we have a new world...
And use Redpower2. Little more expensive to start piping something, and barely at that, but it's 100x better as far as control, speed, and performance goes.
Do your self and your server a favor use RedPower2 for everything. The only useful thing in BuildCraft at the moment is the quarry and tanks. (Many for dense lava storage)
And once you combine ComputerCraft, RedPower2 frames and sorting. You can build an automated quarry devourer-of-worlds that never stops. Ever.
Don't get me wrong I like a lot of ideas in BuildCraft, but it's poorly written, (thus hard on servers) and allows leaks and is out performed by RedPower2. I'd love to see it make a comeback with version 3 though. :)