This causes it to aggressively batch downloads, and also show up as a mobile device to other clients.

This seems to be the right behavior since metro is a tablet based os. Are there perf. issues with mobile batching?

Due to hysterical raisins, there's an unfortunate conflation of capability and device type in Sync. One either shows up as a phone, and has the capabilities of a 2009-era Android phone (including making N/50 HTTP requests for records -- 100 HTTP requests to grab initial history), or one shows up as a desktop. Bug 617210, which changes that '50', was almost closed as WONTFIX because nobody was using XUL Fennec. I think the right solution here is threefold: 1. Report Metro as non-mobile (not bad IMO, because it's usually on WiFi and has more processing power than a _desktop_ Atom device!) 2. Expand the set of device types in Sync to be more useful to other clients (if we know it's metro, we can show a more suitable icon), and more accurately reflect device capabilities. See Bug 745412 Comment 1. 3. Perhaps decouple parameterization of capabilities like this from device type altogether. This makes sense to me. This bug is #1.

Resolving bugs in the Firefox for Metro product that are fixed on the elm branch. Sorry for the bugspam. Search your email for "bugspam-elm" if you want to find and delete all of these messages at once.