I've stood on a kalai before and ridden a lot of dervishes...my opinion: Kalai is a bit less flexy than a flex 1 dervish, but would most likely break in some over time.  The dervish has a little more nose/tail to play around with, which can be nice (my current board has virtually no nose or tail and it makes reverts difficult.) Also, the Kalai is a bit wider, which I prefer, the dervish always feels a little too narrow for my feet. However, for the money, I would definitely go with the Gravity; they are similar enough in shape, weight, and flex that either would be great all around board.  It's not worth shelling out the extra money for the Loaded logo on it.