Based on what I was told when they came out....the difference between the Pro and Glass stones is in the formulation they use. The Glass stones were made to be able to cut the new high wear resistant steels that are/were emerging.....specifically A2 as I recall. The Glass stones are softer, therefore releasing grit more freely to cut through the harder steels.
I've not used the King stones in a long time....but:
You should be having much trouble jumping from 220 to 800 grit....again, I don't know what the 220 King is like though. But, the 800 should grind pretty fast.
Perhaps adding a 500 grit stone would be beneficial though.
Now, jumping from 800 to 6,000 is kind of a big jump....especially if you're wanting to remove all of the 800 grit scratches. Some people make this jump, but don't want to remove all the scratches leaving a rather toothy edge.
If you want a really highly polished edge, add a 3,000 grit or so in there.
You mention a 30,000 grit stone....I'm ignoring that and assuming you meant 3,000 as 30,000 grit stone is...well, silly.
Now, that's using what you currently have.
Ha....I don't differ much from what Mark said.
(I try not to read other replies first)
Now, if you just want to replace what you have with a good set of low wearing stones, get a combo of Shapton Pro's:http://www.chefknivestogo.com/shpro3pcset.html