I've seen some very odd behavior, in particular with Coinchoose.  I would be wary of any sites like this that also manage their own pools.

Why not do your own research?  I find that picking two or three coins that I feel have potential and sticking with them has been the most profitable way to go.  This way you can follow them closely, know when diff changes are about to occur, and have a better feel for the market direction at any given time.

Multipool's go against the greater good of the community as a whole.  They often bring in 10x the normal hashrate of the coin then abandon it when the difficulty rises.  This leaves the coin stuck in a state where blocks are being solved far less frequently than intended.  This is good for no coin.

Even ASIC manufacturers have the decency to give up huge profit potential by only selling and shipping a limited supply of ASICs to the market to battle this kind of disruption.