You should be using the sencha touch 2.2 proxy if you're on 2.2 now as that works fine for me. It filters using queries on the database with the filters param rather than remoteFilters but this works just fine.
I would recommend people switch over.
As for persistancy, please be aware that sqlite and websql are different things. They happen to share, for the most part, their query language, but here is the main difference:
- websql is a browser based database implementation. Sometimes it works on a sqlite backend. The W3C have abandoned the specification for this since 2010, but it remains implemented in nearly all modern browsers. IT IS NOT TRULY PERSISTENT! Any user can delete the data from the browser at any time they wish.