yes protected batteries are best when used in series.
in a series configuration the VOLTAGE increases, so your protection curcuit, say its good for 2amps, will be the same 2 amps, reguardless of voltage.
the "total curcuit path" of the battereis will be going through each 2amp protection curcuit.
protected cells of the same type/brand can easily be applied in parellel, and the short curcuit cutoff amps would become SOMEWHAT cumulative. like put 2x2amp protected batteries together you will get 4Amp when they are perfectally balanced and perfectally connected. and you should be able to get a good 3 amps even if they are off a bit.
(discussing amps of juice before the protection kicks in, not the batterys own capacity)
think of your protection like a "fuse" of sorts, it is rated for total amperage, current or whatever you want to call the "FLOW" of electrons.
