I don't know how it was in the US, but overhere in Europe the Delta had suspension and the Killer not. For me the back then pretty breathtaking first Super V3000 (with m900 and purple bling) and the Killers are the Cannondales I like most. I prefer the Killer over the Delta as to me the Headshock isn't eastheticly very pleasing.

Don't know exactly why they switch to the more traditional design. I think because it was lighter. To me they lost much of the character then and I am not really interested in lightweight.

I think the added stiffnes because of the Killer/Delta design is more theoretical, as the diamant shaped also don't face stiffness problems.

If I remember correctly the change was made in '95. The 1st year the Delta design was still available, but on request.