Do I call GetCache("cacheName") for every DataCache object request, or do I make one static at the time DataCache factory is initialized and use that for all calls?
I suppose really the answer should be; try it both ways and see if there's a difference, but one static DataCache seems to me to make more sense than a corresponding call to GetCache for every call to Get.
That 'Pushing Client Performance' article suggests that there's a sweet spot where the number of DataCacheFactory instances gets you maximum performance beyond which the memory overhead starts working against you - it's a shame they didn't give any guidelines (or even a rule of thumb) on where this spot might be.
I haven't come across any documentation on maximising performance - I think AppFabric is still too new for these guidelines to have been shaken out yet. I did have a look in the Contents for the Pro AppFabric book, but it seems much more concerned generally with the workflow (Dublin) side of AppFabric rather than the caching (Velocity) piece.
One thing I would say though: is there any possibility for you to cache 'chunkier' objects so you can make fewer calls to Get? Could you cache collections rather than individual objects and then unpack the collections on the client? 700 cache gets per page load seems to me to be a huge number!