Well, Dynamic Alternate Power applies for each additional 'spell' that Magic has, but essentially yes, and you can use plain old Alternate Power if you don't need to keep the others running when you switch powers(any powers that are not Instant or Lasting stop working when you switch, and if it's Dynamic Alternate, Concentration,Sustained, and Continous powers rank up and down as appropriate, even if already cast, so they're easier to get through).
Plain Alternate Power however, is much simpler to rotate arrays of powers(which can contain fairly elaborate combinations, linked and such) in and out, as it can be difficult to gauge which powers get what power feats/extras enabled.