I also support the swapping types / makes / models approach. Broadens the experience base and adds a bit of interest.. (Suggested that theory to the missus once; didnt go over well...)
We usually do our basic training in J160, then for navexes we swap all students to one of our J230s. Even though they are all Jabirus, the characteristics are quite different.
Also, when students are no longer students and want to private hire to go away for a day or more, they are likely to go for the J230; the hire rate per NM is actually less than the J160 and they get there earlier!
Also, for those moving on to GA, the J230 is closer in handling to the heavier GA a/c.