The attached two articles, written by professional test pilots, explain the extremely high desirability of the larger tail on the 320/360.  They also admit that the small tail is usable (duh) but recommend VFR only.  

In a private conversation with one of them (Doug Shane of Scaled Composites) he told me that the lateral-directional handling qualities were surprisingly also improved with the bigger tail.  There is no aerodynamic reason for this, and he suspects that he was devoting less than his full mental bandwidth to the pitch axis with the big tail, thus he could do a better job directionally. 

Anyway, they are well written articles.  My advice -- install the big tail.  The installation problems are pretty trivial.  Lancair did a good job on the retrofit.  However, I'm sure the guys that have the small tails will say that it's not so bad, and that you can get used to it.  The point is, you don't have to.

- Rob Wolf