Depends on whether or not you want a trem-
equipped guitar.
While the 7321 is generally considered to be an excellent guitar for it's price, it's hard-tailed and therefore doesn't have the flexibility of a trem. That may or may not be a good thing, depending upon your view
Oh, and it's much cheaper.
The 1527 has another difference in that the neck is the Prestige type. I chose a 1527 so I could have the option of using the trem. And of course when the Tremol-No is available we'll have the option of switching between hard-tail & trem at the turn of a thumbscrew.
