As I've posted elsewhere, I've been working on a version of BufferedList which allows high performance scrolling of essentially infinite length Lists, a la ExtJS 4.1 infinite grid, using data paging to keep load times and memory consumption low. I had a promising version just about ready to go built on top of PR3, and then PR4 came along, and everything broke. Fair enough, pre-releases come with the warning that APIs will evolve.
More to the point, though, under PR4 the Ext.data.Store implementation removed all support for prefetching or buffering, which I was heavily reliant on (prefetchPage, guaranteeRange, etc). Is there any intent of restoring these APIs or equivalent in the final release, or will I have to implement these as some kind of derived store or mixin? It is a non-trivial amount of work, as I'm sure you know.
Also, it seems that under PR4, all data requests are "paged" requests (have start and limit parameters), which means that in order to just get all records for a particular request, you have to explicitly set the pageSize parameter to some big number. This is a change in behavior from previous releases of Touch and ExtJS, and should probably be noted in the docs.