For a low grit stone I really like one you didn't mention which is the Nubatama 150. I think it's still a good idea to have another low grit stone above it since a 1K or 2K has a bit of a hard time taking out the scratches.
I've used the Beston quite a bit and that is a good low grit stone that's fast but wears quickly (this is true with most low grit stones).
The pink brick is a good stone in the category and I think this is one you should cosider. It's fast,smooth and I like the scratch pattern this stone leaves. It needs a good soaking but after you saturate it the stone holds onto the water pretty well. I recommend you flatten this one and the beston quickly before each session. It's BIG too which I like. http://www.chefknivestogo.com/impibr.html